FM / library

/usr/share/doc/python3-docs/html/_sources/library/

/usr/share/doc/python3-docs/html/_sources/library

Name	Size	Mode	Actions
2to3.rst.txt	15898	0644	edit dl rm
abc.rst.txt	11805	0644	edit dl rm
aifc.rst.txt	7503	0644	edit dl rm
allos.rst.txt	678	0644	edit dl rm
archiving.rst.txt	440	0644	edit dl rm
argparse.rst.txt	77480	0644	edit dl rm
array.rst.txt	10812	0644	edit dl rm
ast.rst.txt	10159	0644	edit dl rm
asynchat.rst.txt	8528	0644	edit dl rm
asyncio-dev.rst.txt	13398	0644	edit dl rm
asyncio-eventloop.rst.txt	33701	0644	edit dl rm
asyncio-eventloops.rst.txt	7660	0644	edit dl rm
asyncio-protocol.rst.txt	25170	0644	edit dl rm
asyncio-queue.rst.txt	4328	0644	edit dl rm
asyncio-stream.rst.txt	14363	0644	edit dl rm
asyncio-subprocess.rst.txt	15544	0644	edit dl rm
asyncio-sync.rst.txt	9078	0644	edit dl rm
asyncio-task.rst.txt	25406	0644	edit dl rm
asyncio.rst.txt	2272	0644	edit dl rm
asyncore.rst.txt	13624	0644	edit dl rm
atexit.rst.txt	3669	0644	edit dl rm
audioop.rst.txt	10712	0644	edit dl rm
base64.rst.txt	10371	0644	edit dl rm
bdb.rst.txt	12985	0644	edit dl rm
binary.rst.txt	654	0644	edit dl rm
binascii.rst.txt	6539	0644	edit dl rm
binhex.rst.txt	1709	0644	edit dl rm
bisect.rst.txt	5398	0644	edit dl rm
builtins.rst.txt	1465	0644	edit dl rm
bz2.rst.txt	8825	0644	edit dl rm
calendar.rst.txt	10988	0644	edit dl rm
cgi.rst.txt	22650	0644	edit dl rm
cgitb.rst.txt	2918	0644	edit dl rm
chunk.rst.txt	5094	0644	edit dl rm
cmath.rst.txt	9326	0644	edit dl rm
cmd.rst.txt	13795	0644	edit dl rm
code.rst.txt	7817	0644	edit dl rm
codecs.rst.txt	75564	0644	edit dl rm
codeop.rst.txt	3021	0644	edit dl rm
collections.abc.rst.txt	12861	0644	edit dl rm
collections.rst.txt	46063	0644	edit dl rm
colorsys.rst.txt	1820	0644	edit dl rm
compileall.rst.txt	8975	0644	edit dl rm
concurrency.rst.txt	673	0644	edit dl rm
concurrent.futures.rst.txt	16910	0644	edit dl rm
concurrent.rst.txt	171	0644	edit dl rm
configparser.rst.txt	48756	0644	edit dl rm
constants.rst.txt	3331	0644	edit dl rm
contextlib.rst.txt	28175	0644	edit dl rm
copy.rst.txt	3378	0644	edit dl rm
copyreg.rst.txt	2182	0644	edit dl rm
crypt.rst.txt	5122	0644	edit dl rm
crypto.rst.txt	411	0644	edit dl rm
csv.rst.txt	19902	0644	edit dl rm
ctypes.rst.txt	88613	0644	edit dl rm
curses.ascii.rst.txt	8920	0644	edit dl rm
curses.panel.rst.txt	2764	0644	edit dl rm
curses.rst.txt	76397	0644	edit dl rm
custominterp.rst.txt	569	0644	edit dl rm
datatypes.rst.txt	751	0644	edit dl rm
datetime.rst.txt	90524	0644	edit dl rm
dbm.rst.txt	14293	0644	edit dl rm
debug.rst.txt	471	0644	edit dl rm
decimal.rst.txt	74869	0644	edit dl rm
development.rst.txt	704	0644	edit dl rm
difflib.rst.txt	29861	0644	edit dl rm
dis.rst.txt	32567	0644	edit dl rm
distribution.rst.txt	452	0644	edit dl rm
distutils.rst.txt	1974	0644	edit dl rm
doctest.rst.txt	71743	0644	edit dl rm
dummy_threading.rst.txt	784	0644	edit dl rm
email.charset.rst.txt	9293	0644	edit dl rm
email.compat32-message.rst.txt	33493	0644	edit dl rm
email.contentmanager.rst.txt	9112	0644	edit dl rm
email.encoders.rst.txt	2715	0644	edit dl rm
email.errors.rst.txt	4792	0644	edit dl rm
email.examples.rst.txt	1915	0644	edit dl rm
email.generator.rst.txt	13637	0644	edit dl rm
email.header.rst.txt	9188	0644	edit dl rm
email.headerregistry.rst.txt	17957	0644	edit dl rm
email.iterators.rst.txt	2795	0644	edit dl rm
email.message.rst.txt	33008	0644	edit dl rm
email.mime.rst.txt	11721	0644	edit dl rm
email.parser.rst.txt	14092	0644	edit dl rm
email.policy.rst.txt	27022	0644	edit dl rm
email.rst.txt	6785	0644	edit dl rm
email.util.rst.txt	9214	0644	edit dl rm
ensurepip.rst.txt	4987	0644	edit dl rm
enum.rst.txt	32751	0644	edit dl rm
errno.rst.txt	6811	0644	edit dl rm
exceptions.rst.txt	25570	0644	edit dl rm
faulthandler.rst.txt	6136	0644	edit dl rm
fcntl.rst.txt	7152	0644	edit dl rm
filecmp.rst.txt	5623	0644	edit dl rm
fileformats.rst.txt	287	0644	edit dl rm
fileinput.rst.txt	8051	0644	edit dl rm
filesys.rst.txt	961	0644	edit dl rm
fnmatch.rst.txt	3103	0644	edit dl rm
formatter.rst.txt	13242	0644	edit dl rm
fpectl.rst.txt	4180	0644	edit dl rm
fractions.rst.txt	6364	0644	edit dl rm
frameworks.rst.txt	391	0644	edit dl rm
ftplib.rst.txt	17552	0644	edit dl rm
functional.rst.txt	365	0644	edit dl rm
functions.rst.txt	71621	0644	edit dl rm
functools.rst.txt	18503	0644	edit dl rm
gc.rst.txt	9694	0644	edit dl rm
getopt.rst.txt	6557	0644	edit dl rm
getpass.rst.txt	1882	0644	edit dl rm
gettext.rst.txt	25588	0644	edit dl rm
glob.rst.txt	3508	0644	edit dl rm
grp.rst.txt	2417	0644	edit dl rm
gzip.rst.txt	8301	0644	edit dl rm
hashlib.rst.txt	26523	0644	edit dl rm
heapq.rst.txt	13402	0644	edit dl rm
hmac.rst.txt	4020	0644	edit dl rm
html.entities.rst.txt	1319	0644	edit dl rm
html.parser.rst.txt	11275	0644	edit dl rm
html.rst.txt	1304	0644	edit dl rm
http.client.rst.txt	18870	0644	edit dl rm
http.cookiejar.rst.txt	27832	0644	edit dl rm
http.cookies.rst.txt	8645	0644	edit dl rm
http.rst.txt	7096	0644	edit dl rm
http.server.rst.txt	17639	0644	edit dl rm
i18n.rst.txt	408	0644	edit dl rm
idle.rst.txt	25834	0644	edit dl rm
imaplib.rst.txt	20367	0644	edit dl rm
imghdr.rst.txt	2938	0644	edit dl rm
imp.rst.txt	15548	0644	edit dl rm
importlib.rst.txt	53563	0644	edit dl rm
index.rst.txt	2258	0644	edit dl rm
inspect.rst.txt	53928	0644	edit dl rm
internet.rst.txt	992	0644	edit dl rm
intro.rst.txt	2645	0644	edit dl rm
io.rst.txt	40328	0644	edit dl rm
ipaddress.rst.txt	32340	0644	edit dl rm
ipc.rst.txt	649	0644	edit dl rm
itertools.rst.txt	38459	0644	edit dl rm
json.rst.txt	27876	0644	edit dl rm
keyword.rst.txt	617	0644	edit dl rm
language.rst.txt	522	0644	edit dl rm
linecache.rst.txt	2408	0644	edit dl rm
locale.rst.txt	25470	0644	edit dl rm
logging.config.rst.txt	33886	0644	edit dl rm
logging.handlers.rst.txt	42497	0644	edit dl rm
logging.rst.txt	60479	0644	edit dl rm
lzma.rst.txt	17361	0644	edit dl rm
macpath.rst.txt	707	0644	edit dl rm
mailbox.rst.txt	63055	0644	edit dl rm
mailcap.rst.txt	3691	0644	edit dl rm
markup.rst.txt	679	0644	edit dl rm
marshal.rst.txt	4855	0644	edit dl rm
math.rst.txt	14375	0644	edit dl rm
mimetypes.rst.txt	9839	0644	edit dl rm
misc.rst.txt	247	0644	edit dl rm
mm.rst.txt	431	0644	edit dl rm
mmap.rst.txt	11232	0644	edit dl rm
modulefinder.rst.txt	3240	0644	edit dl rm
modules.rst.txt	355	0644	edit dl rm
msilib.rst.txt	18612	0644	edit dl rm
msvcrt.rst.txt	4392	0644	edit dl rm
multiprocessing.rst.txt	104494	0644	edit dl rm
netdata.rst.txt	339	0644	edit dl rm
netrc.rst.txt	3007	0644	edit dl rm
nis.rst.txt	1993	0644	edit dl rm
nntplib.rst.txt	21821	0644	edit dl rm
numbers.rst.txt	8089	0644	edit dl rm
numeric.rst.txt	696	0644	edit dl rm
operator.rst.txt	18989	0644	edit dl rm
optparse.rst.txt	76996	0644	edit dl rm
os.path.rst.txt	16419	0644	edit dl rm
os.rst.txt	137534	0644	edit dl rm
ossaudiodev.rst.txt	17845	0644	edit dl rm
othergui.rst.txt	2822	0644	edit dl rm
parser.rst.txt	15148	0644	edit dl rm
pathlib.rst.txt	30045	0644	edit dl rm
pdb.rst.txt	19454	0644	edit dl rm
persistence.rst.txt	591	0644	edit dl rm
pickle.rst.txt	37440	0644	edit dl rm
pickletools.rst.txt	3729	0644	edit dl rm
pipes.rst.txt	2557	0644	edit dl rm
pkgutil.rst.txt	8730	0644	edit dl rm
platform.rst.txt	9624	0644	edit dl rm
plistlib.rst.txt	7398	0644	edit dl rm
poplib.rst.txt	8197	0644	edit dl rm
posix.rst.txt	3694	0644	edit dl rm
pprint.rst.txt	14274	0644	edit dl rm
profile.rst.txt	27969	0644	edit dl rm
pty.rst.txt	3123	0644	edit dl rm
pwd.rst.txt	2739	0644	edit dl rm
pyclbr.rst.txt	3297	0644	edit dl rm
pydoc.rst.txt	4688	0644	edit dl rm
pyexpat.rst.txt	28620	0644	edit dl rm
python.rst.txt	475	0644	edit dl rm
py_compile.rst.txt	3851	0644	edit dl rm
queue.rst.txt	7268	0644	edit dl rm
quopri.rst.txt	2571	0644	edit dl rm
random.rst.txt	18503	0644	edit dl rm
re.rst.txt	64936	0644	edit dl rm
readline.rst.txt	11943	0644	edit dl rm
reprlib.rst.txt	5162	0644	edit dl rm
resource.rst.txt	12291	0644	edit dl rm
rlcompleter.rst.txt	2294	0644	edit dl rm
runpy.rst.txt	8285	0644	edit dl rm
sched.rst.txt	4842	0644	edit dl rm
secrets.rst.txt	5930	0644	edit dl rm
select.rst.txt	28175	0644	edit dl rm
selectors.rst.txt	8925	0644	edit dl rm
shelve.rst.txt	8390	0644	edit dl rm
shlex.rst.txt	16441	0644	edit dl rm
shutil.rst.txt	26014	0644	edit dl rm
signal.rst.txt	17218	0644	edit dl rm
site.rst.txt	9628	0644	edit dl rm
smtpd.rst.txt	10806	0644	edit dl rm
smtplib.rst.txt	23439	0644	edit dl rm
sndhdr.rst.txt	1994	0644	edit dl rm
socket.rst.txt	68202	0644	edit dl rm
socketserver.rst.txt	23712	0644	edit dl rm
spwd.rst.txt	2958	0644	edit dl rm
sqlite3.rst.txt	39215	0644	edit dl rm
ssl.rst.txt	96021	0644	edit dl rm
stat.rst.txt	9805	0644	edit dl rm
statistics.rst.txt	15301	0644	edit dl rm
stdtypes.rst.txt	179240	0644	edit dl rm
string.rst.txt	35374	0644	edit dl rm
stringprep.rst.txt	4279	0644	edit dl rm
struct.rst.txt	19581	0644	edit dl rm
subprocess.rst.txt	45793	0644	edit dl rm
sunau.rst.txt	7390	0644	edit dl rm
superseded.rst.txt	258	0644	edit dl rm
symbol.rst.txt	975	0644	edit dl rm
symtable.rst.txt	4964	0644	edit dl rm
sys.rst.txt	58273	0644	edit dl rm
sysconfig.rst.txt	8749	0644	edit dl rm
syslog.rst.txt	4302	0644	edit dl rm
tabnanny.rst.txt	2007	0644	edit dl rm
tarfile.rst.txt	31749	0644	edit dl rm
telnetlib.rst.txt	7899	0644	edit dl rm
tempfile.rst.txt	13857	0644	edit dl rm
termios.rst.txt	3751	0644	edit dl rm
test.rst.txt	25764	0644	edit dl rm
text.rst.txt	584	0644	edit dl rm
textwrap.rst.txt	10519	0644	edit dl rm
threading.rst.txt	39257	0644	edit dl rm
time.rst.txt	32967	0644	edit dl rm
timeit.rst.txt	13000	0644	edit dl rm
tk.rst.txt	1639	0644	edit dl rm
tkinter.rst.txt	33027	0644	edit dl rm
tkinter.scrolledtext.rst.txt	1255	0644	edit dl rm
tkinter.tix.rst.txt	22653	0644	edit dl rm
tkinter.ttk.rst.txt	58489	0644	edit dl rm
token.rst.txt	2607	0644	edit dl rm
tokenize.rst.txt	10002	0644	edit dl rm
trace.rst.txt	6914	0644	edit dl rm
traceback.rst.txt	17854	0644	edit dl rm
tracemalloc.rst.txt	22089	0644	edit dl rm
tty.rst.txt	1097	0644	edit dl rm
turtle.rst.txt	71221	0644	edit dl rm
types.rst.txt	9999	0644	edit dl rm
typing.rst.txt	34332	0644	edit dl rm
undoc.rst.txt	780	0644	edit dl rm
unicodedata.rst.txt	5762	0644	edit dl rm
unittest.mock-examples.rst.txt	46206	0644	edit dl rm
unittest.mock.rst.txt	85991	0644	edit dl rm
unittest.rst.txt	93304	0644	edit dl rm
unix.rst.txt	446	0644	edit dl rm
urllib.error.rst.txt	2199	0644	edit dl rm
urllib.parse.rst.txt	27332	0644	edit dl rm
urllib.request.rst.txt	59360	0644	edit dl rm
urllib.robotparser.rst.txt	2969	0644	edit dl rm
urllib.rst.txt	466	0644	edit dl rm
uu.rst.txt	2387	0644	edit dl rm
uuid.rst.txt	8760	0644	edit dl rm
venv.rst.txt	20621	0644	edit dl rm
warnings.rst.txt	20152	0644	edit dl rm
wave.rst.txt	6870	0644	edit dl rm
weakref.rst.txt	21328	0644	edit dl rm
webbrowser.rst.txt	9783	0644	edit dl rm
windows.rst.txt	272	0644	edit dl rm
winreg.rst.txt	24073	0644	edit dl rm
winsound.rst.txt	5134	0644	edit dl rm
wsgiref.rst.txt	33047	0644	edit dl rm
xdrlib.rst.txt	8078	0644	edit dl rm
xml.dom.minidom.rst.txt	10198	0644	edit dl rm
xml.dom.pulldom.rst.txt	5186	0644	edit dl rm
xml.dom.rst.txt	39507	0644	edit dl rm
xml.etree.elementtree.rst.txt	43871	0644	edit dl rm
xml.rst.txt	6071	0644	edit dl rm
xml.sax.handler.rst.txt	15399	0644	edit dl rm
xml.sax.reader.rst.txt	12133	0644	edit dl rm
xml.sax.rst.txt	7159	0644	edit dl rm
xml.sax.utils.rst.txt	3901	0644	edit dl rm
xmlrpc.client.rst.txt	23071	0644	edit dl rm
xmlrpc.rst.txt	475	0644	edit dl rm
xmlrpc.server.rst.txt	14990	0644	edit dl rm
zipapp.rst.txt	17392	0644	edit dl rm
zipfile.rst.txt	24005	0644	edit dl rm
zipimport.rst.txt	5805	0644	edit dl rm
zlib.rst.txt	13912	0644	edit dl rm
_dummy_thread.rst.txt	762	0644	edit dl rm
_thread.rst.txt	6886	0644	edit dl rm
__future__.rst.txt	5245	0644	edit dl rm
__main__.rst.txt	904	0644	edit dl rm

Edit: /usr/share/doc/python3-docs/html/_sources/library/datetime.rst.txt (90524B)

:mod:`datetime` --- Basic date and time types
=============================================

.. module:: datetime
   :synopsis: Basic date and time types.

.. moduleauthor:: Tim Peters <tim@zope.com>
.. sectionauthor:: Tim Peters <tim@zope.com>
.. sectionauthor:: A.M. Kuchling <amk@amk.ca>

**Source code:** :source:`Lib/datetime.py`

--------------

.. XXX what order should the types be discussed in?

The :mod:`datetime` module supplies classes for manipulating dates and times in
both simple and complex ways.  While date and time arithmetic is supported, the
focus of the implementation is on efficient attribute extraction for output
formatting and manipulation. For related functionality, see also the
:mod:`time` and :mod:`calendar` modules.

There are two kinds of date and time objects: "naive" and "aware".

An aware object has sufficient knowledge of applicable algorithmic and
political time adjustments, such as time zone and daylight saving time
information, to locate itself relative to other aware objects.  An aware object
is used to represent a specific moment in time that is not open to
interpretation [#]_.

A naive object does not contain enough information to unambiguously locate
itself relative to other date/time objects.  Whether a naive object represents
Coordinated Universal Time (UTC), local time, or time in some other timezone is
purely up to the program, just like it is up to the program whether a
particular number represents metres, miles, or mass.  Naive objects are easy to
understand and to work with, at the cost of ignoring some aspects of reality.

For applications requiring aware objects, :class:`.datetime` and :class:`.time`
objects have an optional time zone information attribute, :attr:`!tzinfo`, that
can be set to an instance of a subclass of the abstract :class:`tzinfo` class.
These :class:`tzinfo` objects capture information about the offset from UTC
time, the time zone name, and whether Daylight Saving Time is in effect.  Note
that only one concrete :class:`tzinfo` class, the :class:`timezone` class, is
supplied by the :mod:`datetime` module.  The :class:`timezone` class can
represent simple timezones with fixed offset from UTC, such as UTC itself or
North American EST and EDT timezones.  Supporting timezones at deeper levels of
detail is up to the application.  The rules for time adjustment across the
world are more political than rational, change frequently, and there is no
standard suitable for every application aside from UTC.

The :mod:`datetime` module exports the following constants:

.. data:: MINYEAR

The smallest year number allowed in a :class:`date` or :class:`.datetime` object.
   :const:`MINYEAR` is ``1``.

.. data:: MAXYEAR

The largest year number allowed in a :class:`date` or :class:`.datetime` object.
   :const:`MAXYEAR` is ``9999``.

.. seealso::

Module :mod:`calendar`
      General calendar related functions.

Module :mod:`time`
      Time access and conversions.

Available Types
---------------

.. class:: date
   :noindex:

An idealized naive date, assuming the current Gregorian calendar always was, and
   always will be, in effect. Attributes: :attr:`year`, :attr:`month`, and
   :attr:`day`.

.. class:: time
   :noindex:

An idealized time, independent of any particular day, assuming that every day
   has exactly 24\*60\*60 seconds (there is no notion of "leap seconds" here).
   Attributes: :attr:`hour`, :attr:`minute`, :attr:`second`, :attr:`microsecond`,
   and :attr:`.tzinfo`.

.. class:: datetime
   :noindex:

A combination of a date and a time. Attributes: :attr:`year`, :attr:`month`,
   :attr:`day`, :attr:`hour`, :attr:`minute`, :attr:`second`, :attr:`microsecond`,
   and :attr:`.tzinfo`.

.. class:: timedelta
   :noindex:

A duration expressing the difference between two :class:`date`, :class:`.time`,
   or :class:`.datetime` instances to microsecond resolution.

.. class:: tzinfo
   :noindex:

An abstract base class for time zone information objects.  These are used by the
   :class:`.datetime` and :class:`.time` classes to provide a customizable notion of
   time adjustment (for example, to account for time zone and/or daylight saving
   time).

.. class:: timezone
   :noindex:

A class that implements the :class:`tzinfo` abstract base class as a
   fixed offset from the UTC.

.. versionadded:: 3.2

Objects of these types are immutable.

Objects of the :class:`date` type are always naive.

An object of type :class:`.time` or :class:`.datetime` may be naive or aware.
A :class:`.datetime` object *d* is aware if ``d.tzinfo`` is not ``None`` and
``d.tzinfo.utcoffset(d)`` does not return ``None``.  If ``d.tzinfo`` is
``None``, or if ``d.tzinfo`` is not ``None`` but ``d.tzinfo.utcoffset(d)``
returns ``None``, *d* is naive.  A :class:`.time` object *t* is aware
if ``t.tzinfo`` is not ``None`` and ``t.tzinfo.utcoffset(None)`` does not return
``None``.  Otherwise, *t* is naive.

The distinction between naive and aware doesn't apply to :class:`timedelta`
objects.

Subclass relationships::

object
       timedelta
       tzinfo
           timezone
       time
       date
           datetime

.. _datetime-timedelta:

:class:`timedelta` Objects
--------------------------

A :class:`timedelta` object represents a duration, the difference between two
dates or times.

.. class:: timedelta(days=0, seconds=0, microseconds=0, milliseconds=0, minutes=0, hours=0, weeks=0)

All arguments are optional and default to ``0``.  Arguments may be integers
   or floats, and may be positive or negative.

Only *days*, *seconds* and *microseconds* are stored internally.  Arguments are
   converted to those units:

* A millisecond is converted to 1000 microseconds.
   * A minute is converted to 60 seconds.
   * An hour is converted to 3600 seconds.
   * A week is converted to 7 days.

and days, seconds and microseconds are then normalized so that the
   representation is unique, with

* ``0 <= microseconds < 1000000``
   * ``0 <= seconds < 3600*24`` (the number of seconds in one day)
   * ``-999999999 <= days <= 999999999``

If any argument is a float and there are fractional microseconds,
   the fractional microseconds left over from all arguments are
   combined and their sum is rounded to the nearest microsecond using
   round-half-to-even tiebreaker.  If no argument is a float, the
   conversion and normalization processes are exact (no information is
   lost).

If the normalized value of days lies outside the indicated range,
   :exc:`OverflowError` is raised.

Note that normalization of negative values may be surprising at first. For
   example,

>>> from datetime import timedelta
      >>> d = timedelta(microseconds=-1)
      >>> (d.days, d.seconds, d.microseconds)
      (-1, 86399, 999999)

Class attributes are:

.. attribute:: timedelta.min

The most negative :class:`timedelta` object, ``timedelta(-999999999)``.

.. attribute:: timedelta.max

The most positive :class:`timedelta` object, ``timedelta(days=999999999,
   hours=23, minutes=59, seconds=59, microseconds=999999)``.

.. attribute:: timedelta.resolution

The smallest possible difference between non-equal :class:`timedelta` objects,
   ``timedelta(microseconds=1)``.

Note that, because of normalization, ``timedelta.max`` > ``-timedelta.min``.
``-timedelta.max`` is not representable as a :class:`timedelta` object.

Instance attributes (read-only):

Supported operations:

.. XXX this table is too wide!

+--------------------------------+-----------------------------------------------+
| Operation                      | Result                                        |
+================================+===============================================+
| ``t1 = t2 + t3``               | Sum of *t2* and *t3*. Afterwards *t1*-*t2* == |
|                                | *t3* and *t1*-*t3* == *t2* are true. (1)      |
+--------------------------------+-----------------------------------------------+
| ``t1 = t2 - t3``               | Difference of *t2* and *t3*. Afterwards *t1*  |
|                                | == *t2* - *t3* and *t2* == *t1* + *t3* are    |
|                                | true. (1)(6)                                  |
+--------------------------------+-----------------------------------------------+
| ``t1 = t2 * i or t1 = i * t2`` | Delta multiplied by an integer.               |
|                                | Afterwards *t1* // i == *t2* is true,         |
|                                | provided ``i != 0``.                          |
+--------------------------------+-----------------------------------------------+
|                                | In general, *t1* \* i == *t1* \* (i-1) + *t1* |
|                                | is true. (1)                                  |
+--------------------------------+-----------------------------------------------+
| ``t1 = t2 * f or t1 = f * t2`` | Delta multiplied by a float. The result is    |
|                                | rounded to the nearest multiple of            |
|                                | timedelta.resolution using round-half-to-even.|
+--------------------------------+-----------------------------------------------+
| ``f = t2 / t3``                | Division (3) of *t2* by *t3*.  Returns a      |
|                                | :class:`float` object.                        |
+--------------------------------+-----------------------------------------------+
| ``t1 = t2 / f or t1 = t2 / i`` | Delta divided by a float or an int. The result|
|                                | is rounded to the nearest multiple of         |
|                                | timedelta.resolution using round-half-to-even.|
+--------------------------------+-----------------------------------------------+
| ``t1 = t2 // i`` or            | The floor is computed and the remainder (if   |
| ``t1 = t2 // t3``              | any) is thrown away.  In the second case, an  |
|                                | integer is returned. (3)                      |
+--------------------------------+-----------------------------------------------+
| ``t1 = t2 % t3``               | The remainder is computed as a                |
|                                | :class:`timedelta` object. (3)                |
+--------------------------------+-----------------------------------------------+
| ``q, r = divmod(t1, t2)``      | Computes the quotient and the remainder:      |
|                                | ``q = t1 // t2`` (3) and ``r = t1 % t2``.     |
|                                | q is an integer and r is a :class:`timedelta` |
|                                | object.                                       |
+--------------------------------+-----------------------------------------------+
| ``+t1``                        | Returns a :class:`timedelta` object with the  |
|                                | same value. (2)                               |
+--------------------------------+-----------------------------------------------+
| ``-t1``                        | equivalent to :class:`timedelta`\             |
|                                | (-*t1.days*, -*t1.seconds*,                   |
|                                | -*t1.microseconds*), and to *t1*\* -1. (1)(4) |
+--------------------------------+-----------------------------------------------+
| ``abs(t)``                     | equivalent to +\ *t* when ``t.days >= 0``, and|
|                                | to -*t* when ``t.days < 0``. (2)              |
+--------------------------------+-----------------------------------------------+
| ``str(t)``                     | Returns a string in the form                  |
|                                | ``[D day[s], ][H]H:MM:SS[.UUUUUU]``, where D  |
|                                | is negative for negative ``t``. (5)           |
+--------------------------------+-----------------------------------------------+
| ``repr(t)``                    | Returns a string in the form                  |
|                                | ``datetime.timedelta(D[, S[, U]])``, where D  |
|                                | is negative for negative ``t``. (5)           |
+--------------------------------+-----------------------------------------------+

Notes:

(1)
   This is exact, but may overflow.

(2)
   This is exact, and cannot overflow.

(3)
   Division by 0 raises :exc:`ZeroDivisionError`.

(4)
   -*timedelta.max* is not representable as a :class:`timedelta` object.

(5)
  String representations of :class:`timedelta` objects are normalized
  similarly to their internal representation.  This leads to somewhat
  unusual results for negative timedeltas.  For example:

>>> timedelta(hours=-5)
  datetime.timedelta(-1, 68400)
  >>> print(_)
  -1 day, 19:00:00

(6)
   The expression ``t2 - t3`` will always be equal to the expression ``t2 + (-t3)`` except
   when t3 is equal to ``timedelta.max``; in that case the former will produce a result
   while the latter will overflow.

In addition to the operations listed above :class:`timedelta` objects support
certain additions and subtractions with :class:`date` and :class:`.datetime`
objects (see below).

.. versionchanged:: 3.2
   Floor division and true division of a :class:`timedelta` object by another
   :class:`timedelta` object are now supported, as are remainder operations and
   the :func:`divmod` function.  True division and multiplication of a
   :class:`timedelta` object by a :class:`float` object are now supported.

Comparisons of :class:`timedelta` objects are supported with the
:class:`timedelta` object representing the smaller duration considered to be the
smaller timedelta. In order to stop mixed-type comparisons from falling back to
the default comparison by object address, when a :class:`timedelta` object is
compared to an object of a different type, :exc:`TypeError` is raised unless the
comparison is ``==`` or ``!=``.  The latter cases return :const:`False` or
:const:`True`, respectively.

:class:`timedelta` objects are :term:`hashable` (usable as dictionary keys), support
efficient pickling, and in Boolean contexts, a :class:`timedelta` object is
considered to be true if and only if it isn't equal to ``timedelta(0)``.

Instance methods:

.. method:: timedelta.total_seconds()

Return the total number of seconds contained in the duration. Equivalent to
   ``td / timedelta(seconds=1)``.

Note that for very large time intervals (greater than 270 years on
   most platforms) this method will lose microsecond accuracy.

.. versionadded:: 3.2

Example usage:

>>> from datetime import timedelta
    >>> year = timedelta(days=365)
    >>> another_year = timedelta(weeks=40, days=84, hours=23,
    ...                          minutes=50, seconds=600)  # adds up to 365 days
    >>> year.total_seconds()
    31536000.0
    >>> year == another_year
    True
    >>> ten_years = 10 * year
    >>> ten_years, ten_years.days // 365
    (datetime.timedelta(3650), 10)
    >>> nine_years = ten_years - year
    >>> nine_years, nine_years.days // 365
    (datetime.timedelta(3285), 9)
    >>> three_years = nine_years // 3;
    >>> three_years, three_years.days // 365
    (datetime.timedelta(1095), 3)
    >>> abs(three_years - ten_years) == 2 * three_years + year
    True

.. _datetime-date:

:class:`date` Objects
---------------------

A :class:`date` object represents a date (year, month and day) in an idealized
calendar, the current Gregorian calendar indefinitely extended in both
directions.  January 1 of year 1 is called day number 1, January 2 of year 1 is
called day number 2, and so on.  This matches the definition of the "proleptic
Gregorian" calendar in Dershowitz and Reingold's book Calendrical Calculations,
where it's the base calendar for all computations.  See the book for algorithms
for converting between proleptic Gregorian ordinals and many other calendar
systems.

.. class:: date(year, month, day)

All arguments are required.  Arguments may be integers, in the following
   ranges:

* ``MINYEAR <= year <= MAXYEAR``
   * ``1 <= month <= 12``
   * ``1 <= day <= number of days in the given month and year``

If an argument outside those ranges is given, :exc:`ValueError` is raised.

Other constructors, all class methods:

.. classmethod:: date.today()

Return the current local date.  This is equivalent to
   ``date.fromtimestamp(time.time())``.

.. classmethod:: date.fromtimestamp(timestamp)

Return the local date corresponding to the POSIX timestamp, such as is returned
   by :func:`time.time`.  This may raise :exc:`OverflowError`, if the timestamp is out
   of the range of values supported by the platform C :c:func:`localtime` function,
   and :exc:`OSError` on :c:func:`localtime` failure.
   It's common for this to be restricted to years from 1970 through 2038.  Note
   that on non-POSIX systems that include leap seconds in their notion of a
   timestamp, leap seconds are ignored by :meth:`fromtimestamp`.

.. versionchanged:: 3.3
      Raise :exc:`OverflowError` instead of :exc:`ValueError` if the timestamp
      is out of the range of values supported by the platform C
      :c:func:`localtime` function. Raise :exc:`OSError` instead of
      :exc:`ValueError` on :c:func:`localtime` failure.

.. classmethod:: date.fromordinal(ordinal)

Return the date corresponding to the proleptic Gregorian ordinal, where January
   1 of year 1 has ordinal 1.  :exc:`ValueError` is raised unless ``1 <= ordinal <=
   date.max.toordinal()``. For any date *d*, ``date.fromordinal(d.toordinal()) ==
   d``.

Class attributes:

.. attribute:: date.min

The earliest representable date, ``date(MINYEAR, 1, 1)``.

.. attribute:: date.max

The latest representable date, ``date(MAXYEAR, 12, 31)``.

.. attribute:: date.resolution

The smallest possible difference between non-equal date objects,
   ``timedelta(days=1)``.

Instance attributes (read-only):

.. attribute:: date.year

Between :const:`MINYEAR` and :const:`MAXYEAR` inclusive.

.. attribute:: date.month

Between 1 and 12 inclusive.

.. attribute:: date.day

Between 1 and the number of days in the given month of the given year.

Supported operations:

+-------------------------------+----------------------------------------------+
| Operation                     | Result                                       |
+===============================+==============================================+
| ``date2 = date1 + timedelta`` | *date2* is ``timedelta.days`` days removed   |
|                               | from *date1*.  (1)                           |
+-------------------------------+----------------------------------------------+
| ``date2 = date1 - timedelta`` | Computes *date2* such that ``date2 +         |
|                               | timedelta == date1``. (2)                    |
+-------------------------------+----------------------------------------------+
| ``timedelta = date1 - date2`` | \(3)                                         |
+-------------------------------+----------------------------------------------+
| ``date1 < date2``             | *date1* is considered less than *date2* when |
|                               | *date1* precedes *date2* in time. (4)        |
+-------------------------------+----------------------------------------------+

Notes:

(1)
   *date2* is moved forward in time if ``timedelta.days > 0``, or backward if
   ``timedelta.days < 0``.  Afterward ``date2 - date1 == timedelta.days``.
   ``timedelta.seconds`` and ``timedelta.microseconds`` are ignored.
   :exc:`OverflowError` is raised if ``date2.year`` would be smaller than
   :const:`MINYEAR` or larger than :const:`MAXYEAR`.

(2)
   ``timedelta.seconds`` and ``timedelta.microseconds`` are ignored.

(3)
   This is exact, and cannot overflow.  timedelta.seconds and
   timedelta.microseconds are 0, and date2 + timedelta == date1 after.

(4)
   In other words, ``date1 < date2`` if and only if ``date1.toordinal() <
   date2.toordinal()``. Date comparison raises :exc:`TypeError` if
   the other comparand isn't also a :class:`date` object. However,
   ``NotImplemented`` is returned instead if the other comparand has a
   :meth:`timetuple` attribute.  This hook gives other kinds of date objects a
   chance at implementing mixed-type comparison. If not, when a :class:`date`
   object is compared to an object of a different type, :exc:`TypeError` is raised
   unless the comparison is ``==`` or ``!=``.  The latter cases return
   :const:`False` or :const:`True`, respectively.

Dates can be used as dictionary keys. In Boolean contexts, all :class:`date`
objects are considered to be true.

Instance methods:

.. method:: date.replace(year=self.year, month=self.month, day=self.day)

Return a date with the same value, except for those parameters given new
   values by whichever keyword arguments are specified.  For example, if ``d ==
   date(2002, 12, 31)``, then ``d.replace(day=26) == date(2002, 12, 26)``.

.. method:: date.timetuple()

Return a :class:`time.struct_time` such as returned by :func:`time.localtime`.
   The hours, minutes and seconds are 0, and the DST flag is -1. ``d.timetuple()``
   is equivalent to ``time.struct_time((d.year, d.month, d.day, 0, 0, 0,
   d.weekday(), yday, -1))``, where ``yday = d.toordinal() - date(d.year, 1,
   1).toordinal() + 1`` is the day number within the current year starting with
   ``1`` for January 1st.

.. method:: date.toordinal()

Return the proleptic Gregorian ordinal of the date, where January 1 of year 1
   has ordinal 1.  For any :class:`date` object *d*,
   ``date.fromordinal(d.toordinal()) == d``.

.. method:: date.weekday()

Return the day of the week as an integer, where Monday is 0 and Sunday is 6.
   For example, ``date(2002, 12, 4).weekday() == 2``, a Wednesday. See also
   :meth:`isoweekday`.

.. method:: date.isoweekday()

Return the day of the week as an integer, where Monday is 1 and Sunday is 7.
   For example, ``date(2002, 12, 4).isoweekday() == 3``, a Wednesday. See also
   :meth:`weekday`, :meth:`isocalendar`.

.. method:: date.isocalendar()

Return a 3-tuple, (ISO year, ISO week number, ISO weekday).

The ISO calendar is a widely used variant of the Gregorian calendar. See
   https://www.staff.science.uu.nl/~gent0113/calendar/isocalendar.htm for a good
   explanation.

The ISO year consists of 52 or 53 full weeks, and where a week starts on a
   Monday and ends on a Sunday.  The first week of an ISO year is the first
   (Gregorian) calendar week of a year containing a Thursday. This is called week
   number 1, and the ISO year of that Thursday is the same as its Gregorian year.

For example, 2004 begins on a Thursday, so the first week of ISO year 2004
   begins on Monday, 29 Dec 2003 and ends on Sunday, 4 Jan 2004, so that
   ``date(2003, 12, 29).isocalendar() == (2004, 1, 1)`` and ``date(2004, 1,
   4).isocalendar() == (2004, 1, 7)``.

.. method:: date.isoformat()

Return a string representing the date in ISO 8601 format, 'YYYY-MM-DD'.  For
   example, ``date(2002, 12, 4).isoformat() == '2002-12-04'``.

.. method:: date.__str__()

For a date *d*, ``str(d)`` is equivalent to ``d.isoformat()``.

.. method:: date.ctime()

Return a string representing the date, for example ``date(2002, 12,
   4).ctime() == 'Wed Dec 4 00:00:00 2002'``. ``d.ctime()`` is equivalent to
   ``time.ctime(time.mktime(d.timetuple()))`` on platforms where the native C
   :c:func:`ctime` function (which :func:`time.ctime` invokes, but which
   :meth:`date.ctime` does not invoke) conforms to the C standard.

.. method:: date.strftime(format)

Return a string representing the date, controlled by an explicit format string.
   Format codes referring to hours, minutes or seconds will see 0 values. For a
   complete list of formatting directives, see
   :ref:`strftime-strptime-behavior`.

.. method:: date.__format__(format)

Same as :meth:`.date.strftime`. This makes it possible to specify a format
   string for a :class:`.date` object in :ref:`formatted string
   literals <f-strings>` and when using :meth:`str.format`. For a
   complete list of formatting directives, see
   :ref:`strftime-strptime-behavior`.

Example of counting days to an event::

>>> import time
    >>> from datetime import date
    >>> today = date.today()
    >>> today
    datetime.date(2007, 12, 5)
    >>> today == date.fromtimestamp(time.time())
    True
    >>> my_birthday = date(today.year, 6, 24)
    >>> if my_birthday < today:
    ...     my_birthday = my_birthday.replace(year=today.year + 1)
    >>> my_birthday
    datetime.date(2008, 6, 24)
    >>> time_to_birthday = abs(my_birthday - today)
    >>> time_to_birthday.days
    202

Example of working with :class:`date`:

.. doctest::

>>> from datetime import date
    >>> d = date.fromordinal(730920) # 730920th day after 1. 1. 0001
    >>> d
    datetime.date(2002, 3, 11)
    >>> t = d.timetuple()
    >>> for i in t:     # doctest: +SKIP
    ...     print(i)
    2002                # year
    3                   # month
    11                  # day
    0
    0
    0
    0                   # weekday (0 = Monday)
    70                  # 70th day in the year
    -1
    >>> ic = d.isocalendar()
    >>> for i in ic:    # doctest: +SKIP
    ...     print(i)
    2002                # ISO year
    11                  # ISO week number
    1                   # ISO day number ( 1 = Monday )
    >>> d.isoformat()
    '2002-03-11'
    >>> d.strftime("%d/%m/%y")
    '11/03/02'
    >>> d.strftime("%A %d. %B %Y")
    'Monday 11. March 2002'
    >>> 'The {1} is {0:%d}, the {2} is {0:%B}.'.format(d, "day", "month")
    'The day is 11, the month is March.'

.. _datetime-datetime:

:class:`.datetime` Objects
--------------------------

A :class:`.datetime` object is a single object containing all the information
from a :class:`date` object and a :class:`.time` object.  Like a :class:`date`
object, :class:`.datetime` assumes the current Gregorian calendar extended in
both directions; like a time object, :class:`.datetime` assumes there are exactly
3600\*24 seconds in every day.

Constructor:

.. class:: datetime(year, month, day, hour=0, minute=0, second=0, microsecond=0, tzinfo=None, *, fold=0)

The year, month and day arguments are required.  *tzinfo* may be ``None``, or an
   instance of a :class:`tzinfo` subclass.  The remaining arguments may be integers,
   in the following ranges:

* ``MINYEAR <= year <= MAXYEAR``,
   * ``1 <= month <= 12``,
   * ``1 <= day <= number of days in the given month and year``,
   * ``0 <= hour < 24``,
   * ``0 <= minute < 60``,
   * ``0 <= second < 60``,
   * ``0 <= microsecond < 1000000``,
   * ``fold in [0, 1]``.

If an argument outside those ranges is given, :exc:`ValueError` is raised.

.. versionadded:: 3.6
      Added the ``fold`` argument.

Other constructors, all class methods:

.. classmethod:: datetime.today()

Return the current local datetime, with :attr:`.tzinfo` ``None``. This is
   equivalent to ``datetime.fromtimestamp(time.time())``. See also :meth:`now`,
   :meth:`fromtimestamp`.

.. classmethod:: datetime.now(tz=None)

Return the current local date and time.  If optional argument *tz* is ``None``
   or not specified, this is like :meth:`today`, but, if possible, supplies more
   precision than can be gotten from going through a :func:`time.time` timestamp
   (for example, this may be possible on platforms supplying the C
   :c:func:`gettimeofday` function).

If *tz* is not ``None``, it must be an instance of a :class:`tzinfo` subclass, and the
   current date and time are converted to *tz*’s time zone.  In this case the
   result is equivalent to ``tz.fromutc(datetime.utcnow().replace(tzinfo=tz))``.
   See also :meth:`today`, :meth:`utcnow`.

.. classmethod:: datetime.utcnow()

Return the current UTC date and time, with :attr:`.tzinfo` ``None``. This is like
   :meth:`now`, but returns the current UTC date and time, as a naive
   :class:`.datetime` object.  An aware current UTC datetime can be obtained by
   calling ``datetime.now(timezone.utc)``.  See also :meth:`now`.

.. classmethod:: datetime.fromtimestamp(timestamp, tz=None)

Return the local date and time corresponding to the POSIX timestamp, such as is
   returned by :func:`time.time`. If optional argument *tz* is ``None`` or not
   specified, the timestamp is converted to the platform's local date and time, and
   the returned :class:`.datetime` object is naive.

If *tz* is not ``None``, it must be an instance of a :class:`tzinfo` subclass, and the
   timestamp is converted to *tz*’s time zone.  In this case the result is
   equivalent to
   ``tz.fromutc(datetime.utcfromtimestamp(timestamp).replace(tzinfo=tz))``.

:meth:`fromtimestamp` may raise :exc:`OverflowError`, if the timestamp is out of
   the range of values supported by the platform C :c:func:`localtime` or
   :c:func:`gmtime` functions, and :exc:`OSError` on :c:func:`localtime` or
   :c:func:`gmtime` failure.
   It's common for this to be restricted to years in
   1970 through 2038. Note that on non-POSIX systems that include leap seconds in
   their notion of a timestamp, leap seconds are ignored by :meth:`fromtimestamp`,
   and then it's possible to have two timestamps differing by a second that yield
   identical :class:`.datetime` objects. See also :meth:`utcfromtimestamp`.

.. versionchanged:: 3.3
      Raise :exc:`OverflowError` instead of :exc:`ValueError` if the timestamp
      is out of the range of values supported by the platform C
      :c:func:`localtime` or :c:func:`gmtime` functions. Raise :exc:`OSError`
      instead of :exc:`ValueError` on :c:func:`localtime` or :c:func:`gmtime`
      failure.

.. versionchanged:: 3.6
      :meth:`fromtimestamp` may return instances with :attr:`.fold` set to 1.

.. classmethod:: datetime.utcfromtimestamp(timestamp)

Return the UTC :class:`.datetime` corresponding to the POSIX timestamp, with
   :attr:`.tzinfo` ``None``. This may raise :exc:`OverflowError`, if the timestamp is
   out of the range of values supported by the platform C :c:func:`gmtime` function,
   and :exc:`OSError` on :c:func:`gmtime` failure.
   It's common for this to be restricted to years in 1970 through 2038.

To get an aware :class:`.datetime` object, call :meth:`fromtimestamp`::

datetime.fromtimestamp(timestamp, timezone.utc)

On the POSIX compliant platforms, it is equivalent to the following
   expression::

datetime(1970, 1, 1, tzinfo=timezone.utc) + timedelta(seconds=timestamp)

except the latter formula always supports the full years range: between
   :const:`MINYEAR` and :const:`MAXYEAR` inclusive.

.. versionchanged:: 3.3
      Raise :exc:`OverflowError` instead of :exc:`ValueError` if the timestamp
      is out of the range of values supported by the platform C
      :c:func:`gmtime` function. Raise :exc:`OSError` instead of
      :exc:`ValueError` on :c:func:`gmtime` failure.

.. classmethod:: datetime.fromordinal(ordinal)

Return the :class:`.datetime` corresponding to the proleptic Gregorian ordinal,
   where January 1 of year 1 has ordinal 1. :exc:`ValueError` is raised unless ``1
   <= ordinal <= datetime.max.toordinal()``.  The hour, minute, second and
   microsecond of the result are all 0, and :attr:`.tzinfo` is ``None``.

.. classmethod:: datetime.combine(date, time, tzinfo=self.tzinfo)

Return a new :class:`.datetime` object whose date components are equal to the
   given :class:`date` object's, and whose time components
   are equal to the given :class:`.time` object's.  If the *tzinfo*
   argument is provided, its value is used to set the :attr:`.tzinfo` attribute
   of the result, otherwise the :attr:`~.time.tzinfo` attribute of the *time* argument
   is used.

For any :class:`.datetime` object *d*,
   ``d == datetime.combine(d.date(), d.time(), d.tzinfo)``.  If date is a
   :class:`.datetime` object, its time components and :attr:`.tzinfo` attributes
   are ignored.

.. versionchanged:: 3.6
      Added the *tzinfo* argument.

.. classmethod:: datetime.strptime(date_string, format)

Return a :class:`.datetime` corresponding to *date_string*, parsed according to
   *format*.  This is equivalent to ``datetime(*(time.strptime(date_string,
   format)[0:6]))``. :exc:`ValueError` is raised if the date_string and format
   can't be parsed by :func:`time.strptime` or if it returns a value which isn't a
   time tuple. For a complete list of formatting directives, see
   :ref:`strftime-strptime-behavior`.

Class attributes:

.. attribute:: datetime.min

The earliest representable :class:`.datetime`, ``datetime(MINYEAR, 1, 1,
   tzinfo=None)``.

.. attribute:: datetime.max

The latest representable :class:`.datetime`, ``datetime(MAXYEAR, 12, 31, 23, 59,
   59, 999999, tzinfo=None)``.

.. attribute:: datetime.resolution

The smallest possible difference between non-equal :class:`.datetime` objects,
   ``timedelta(microseconds=1)``.

Instance attributes (read-only):

.. attribute:: datetime.year

Between :const:`MINYEAR` and :const:`MAXYEAR` inclusive.

.. attribute:: datetime.month

Between 1 and 12 inclusive.

.. attribute:: datetime.day

Between 1 and the number of days in the given month of the given year.

.. attribute:: datetime.hour

In ``range(24)``.

.. attribute:: datetime.minute

In ``range(60)``.

.. attribute:: datetime.second

In ``range(60)``.

.. attribute:: datetime.microsecond

In ``range(1000000)``.

.. attribute:: datetime.tzinfo

The object passed as the *tzinfo* argument to the :class:`.datetime` constructor,
   or ``None`` if none was passed.

.. attribute:: datetime.fold

In ``[0, 1]``.  Used to disambiguate wall times during a repeated interval.  (A
   repeated interval occurs when clocks are rolled back at the end of daylight saving
   time or when the UTC offset for the current zone is decreased for political reasons.)
   The value 0 (1) represents the earlier (later) of the two moments with the same wall
   time representation.

.. versionadded:: 3.6

Supported operations:

+---------------------------------------+--------------------------------+
| Operation                             | Result                         |
+=======================================+================================+
| ``datetime2 = datetime1 + timedelta`` | \(1)                           |
+---------------------------------------+--------------------------------+
| ``datetime2 = datetime1 - timedelta`` | \(2)                           |
+---------------------------------------+--------------------------------+
| ``timedelta = datetime1 - datetime2`` | \(3)                           |
+---------------------------------------+--------------------------------+
| ``datetime1 < datetime2``             | Compares :class:`.datetime` to |
|                                       | :class:`.datetime`. (4)        |
+---------------------------------------+--------------------------------+

(1)
   datetime2 is a duration of timedelta removed from datetime1, moving forward in
   time if ``timedelta.days`` > 0, or backward if ``timedelta.days`` < 0.  The
   result has the same :attr:`~.datetime.tzinfo` attribute as the input datetime, and
   datetime2 - datetime1 == timedelta after. :exc:`OverflowError` is raised if
   datetime2.year would be smaller than :const:`MINYEAR` or larger than
   :const:`MAXYEAR`. Note that no time zone adjustments are done even if the
   input is an aware object.

(2)
   Computes the datetime2 such that datetime2 + timedelta == datetime1. As for
   addition, the result has the same :attr:`~.datetime.tzinfo` attribute as the input
   datetime, and no time zone adjustments are done even if the input is aware.

(3)
   Subtraction of a :class:`.datetime` from a :class:`.datetime` is defined only if
   both operands are naive, or if both are aware.  If one is aware and the other is
   naive, :exc:`TypeError` is raised.

If both are naive, or both are aware and have the same :attr:`~.datetime.tzinfo` attribute,
   the :attr:`~.datetime.tzinfo` attributes are ignored, and the result is a :class:`timedelta`
   object *t* such that ``datetime2 + t == datetime1``.  No time zone adjustments
   are done in this case.

If both are aware and have different :attr:`~.datetime.tzinfo` attributes, ``a-b`` acts
   as if *a* and *b* were first converted to naive UTC datetimes first.  The
   result is ``(a.replace(tzinfo=None) - a.utcoffset()) - (b.replace(tzinfo=None)
   - b.utcoffset())`` except that the implementation never overflows.

(4)
   *datetime1* is considered less than *datetime2* when *datetime1* precedes
   *datetime2* in time.

If one comparand is naive and the other is aware, :exc:`TypeError`
   is raised if an order comparison is attempted.  For equality
   comparisons, naive instances are never equal to aware instances.

If both comparands are aware, and have the same :attr:`~.datetime.tzinfo` attribute, the
   common :attr:`~.datetime.tzinfo` attribute is ignored and the base datetimes are
   compared.  If both comparands are aware and have different :attr:`~.datetime.tzinfo`
   attributes, the comparands are first adjusted by subtracting their UTC
   offsets (obtained from ``self.utcoffset()``).

.. versionchanged:: 3.3
      Equality comparisons between naive and aware :class:`.datetime`
      instances don't raise :exc:`TypeError`.

.. note::

In order to stop comparison from falling back to the default scheme of comparing
      object addresses, datetime comparison normally raises :exc:`TypeError` if the
      other comparand isn't also a :class:`.datetime` object.  However,
      ``NotImplemented`` is returned instead if the other comparand has a
      :meth:`timetuple` attribute.  This hook gives other kinds of date objects a
      chance at implementing mixed-type comparison.  If not, when a :class:`.datetime`
      object is compared to an object of a different type, :exc:`TypeError` is raised
      unless the comparison is ``==`` or ``!=``.  The latter cases return
      :const:`False` or :const:`True`, respectively.

:class:`.datetime` objects can be used as dictionary keys. In Boolean contexts,
all :class:`.datetime` objects are considered to be true.

Instance methods:

.. method:: datetime.date()

Return :class:`date` object with same year, month and day.

.. method:: datetime.time()

Return :class:`.time` object with same hour, minute, second, microsecond and fold.
   :attr:`.tzinfo` is ``None``.  See also method :meth:`timetz`.

.. versionchanged:: 3.6
      The fold value is copied to the returned :class:`.time` object.

.. method:: datetime.timetz()

Return :class:`.time` object with same hour, minute, second, microsecond, fold, and
   tzinfo attributes.  See also method :meth:`time`.

.. versionchanged:: 3.6
      The fold value is copied to the returned :class:`.time` object.

.. method:: datetime.replace(year=self.year, month=self.month, day=self.day, \
   hour=self.hour, minute=self.minute, second=self.second, microsecond=self.microsecond, \
   tzinfo=self.tzinfo, * fold=0)

Return a datetime with the same attributes, except for those attributes given
   new values by whichever keyword arguments are specified.  Note that
   ``tzinfo=None`` can be specified to create a naive datetime from an aware
   datetime with no conversion of date and time data.

.. versionadded:: 3.6
      Added the ``fold`` argument.

.. method:: datetime.astimezone(tz=None)

Return a :class:`.datetime` object with new :attr:`.tzinfo` attribute *tz*,
   adjusting the date and time data so the result is the same UTC time as
   *self*, but in *tz*'s local time.

If provided, *tz* must be an instance of a :class:`tzinfo` subclass, and its
   :meth:`utcoffset` and :meth:`dst` methods must not return ``None``.  If *self*
   is naive, it is presumed to represent time in the system timezone.

If called without arguments (or with ``tz=None``) the system local
   timezone is assumed for the target timezone.  The ``.tzinfo`` attribute of the converted
   datetime instance will be set to an instance of :class:`timezone`
   with the zone name and offset obtained from the OS.

If ``self.tzinfo`` is *tz*, ``self.astimezone(tz)`` is equal to *self*:  no
   adjustment of date or time data is performed. Else the result is local
   time in the timezone *tz*, representing the same UTC time as *self*:  after
   ``astz = dt.astimezone(tz)``, ``astz - astz.utcoffset()`` will have
   the same date and time data as ``dt - dt.utcoffset()``.

If you merely want to attach a time zone object *tz* to a datetime *dt* without
   adjustment of date and time data, use ``dt.replace(tzinfo=tz)``.  If you
   merely want to remove the time zone object from an aware datetime *dt* without
   conversion of date and time data, use ``dt.replace(tzinfo=None)``.

Note that the default :meth:`tzinfo.fromutc` method can be overridden in a
   :class:`tzinfo` subclass to affect the result returned by :meth:`astimezone`.
   Ignoring error cases, :meth:`astimezone` acts like::

def astimezone(self, tz):
          if self.tzinfo is tz:
              return self
          # Convert self to UTC, and attach the new time zone object.
          utc = (self - self.utcoffset()).replace(tzinfo=tz)
          # Convert from UTC to tz's local time.
          return tz.fromutc(utc)

.. versionchanged:: 3.3
      *tz* now can be omitted.

.. versionchanged:: 3.6
      The :meth:`astimezone` method can now be called on naive instances that
      are presumed to represent system local time.

.. method:: datetime.utcoffset()

If :attr:`.tzinfo` is ``None``, returns ``None``, else returns
   ``self.tzinfo.utcoffset(self)``, and raises an exception if the latter doesn't
   return ``None``, or a :class:`timedelta` object representing a whole number of
   minutes with magnitude less than one day.

.. method:: datetime.dst()

If :attr:`.tzinfo` is ``None``, returns ``None``, else returns
   ``self.tzinfo.dst(self)``, and raises an exception if the latter doesn't return
   ``None``, or a :class:`timedelta` object representing a whole number of minutes
   with magnitude less than one day.

.. method:: datetime.tzname()

If :attr:`.tzinfo` is ``None``, returns ``None``, else returns
   ``self.tzinfo.tzname(self)``, raises an exception if the latter doesn't return
   ``None`` or a string object,

.. method:: datetime.timetuple()

Return a :class:`time.struct_time` such as returned by :func:`time.localtime`.
   ``d.timetuple()`` is equivalent to ``time.struct_time((d.year, d.month, d.day,
   d.hour, d.minute, d.second, d.weekday(), yday, dst))``, where ``yday =
   d.toordinal() - date(d.year, 1, 1).toordinal() + 1`` is the day number within
   the current year starting with ``1`` for January 1st. The :attr:`tm_isdst` flag
   of the result is set according to the :meth:`dst` method: :attr:`.tzinfo` is
   ``None`` or :meth:`dst` returns ``None``, :attr:`tm_isdst` is set to ``-1``;
   else if :meth:`dst` returns a non-zero value, :attr:`tm_isdst` is set to ``1``;
   else :attr:`tm_isdst` is set to ``0``.

.. method:: datetime.utctimetuple()

If :class:`.datetime` instance *d* is naive, this is the same as
   ``d.timetuple()`` except that :attr:`tm_isdst` is forced to 0 regardless of what
   ``d.dst()`` returns.  DST is never in effect for a UTC time.

If *d* is aware, *d* is normalized to UTC time, by subtracting
   ``d.utcoffset()``, and a :class:`time.struct_time` for the
   normalized time is returned.  :attr:`tm_isdst` is forced to 0. Note
   that an :exc:`OverflowError` may be raised if *d*.year was
   ``MINYEAR`` or ``MAXYEAR`` and UTC adjustment spills over a year
   boundary.

.. method:: datetime.toordinal()

Return the proleptic Gregorian ordinal of the date.  The same as
   ``self.date().toordinal()``.

.. method:: datetime.timestamp()

Return POSIX timestamp corresponding to the :class:`.datetime`
   instance.  The return value is a :class:`float` similar to that
   returned by :func:`time.time`.

Naive :class:`.datetime` instances are assumed to represent local
   time and this method relies on the platform C :c:func:`mktime`
   function to perform the conversion.  Since :class:`.datetime`
   supports wider range of values than :c:func:`mktime` on many
   platforms, this method may raise :exc:`OverflowError` for times far
   in the past or far in the future.

For aware :class:`.datetime` instances, the return value is computed
   as::

(dt - datetime(1970, 1, 1, tzinfo=timezone.utc)).total_seconds()

.. versionadded:: 3.3

.. versionchanged:: 3.6
      The :meth:`timestamp` method uses the :attr:`.fold` attribute to
      disambiguate the times during a repeated interval.

.. note::

There is no method to obtain the POSIX timestamp directly from a
      naive :class:`.datetime` instance representing UTC time.  If your
      application uses this convention and your system timezone is not
      set to UTC, you can obtain the POSIX timestamp by supplying
      ``tzinfo=timezone.utc``::

timestamp = dt.replace(tzinfo=timezone.utc).timestamp()

or by calculating the timestamp directly::

timestamp = (dt - datetime(1970, 1, 1)) / timedelta(seconds=1)

.. method:: datetime.weekday()

Return the day of the week as an integer, where Monday is 0 and Sunday is 6.
   The same as ``self.date().weekday()``. See also :meth:`isoweekday`.

.. method:: datetime.isoweekday()

Return the day of the week as an integer, where Monday is 1 and Sunday is 7.
   The same as ``self.date().isoweekday()``. See also :meth:`weekday`,
   :meth:`isocalendar`.

.. method:: datetime.isocalendar()

Return a 3-tuple, (ISO year, ISO week number, ISO weekday).  The same as
   ``self.date().isocalendar()``.

.. method:: datetime.isoformat(sep='T', timespec='auto')

Return a string representing the date and time in ISO 8601 format,
   YYYY-MM-DDTHH:MM:SS.mmmmmm or, if :attr:`microsecond` is 0,
   YYYY-MM-DDTHH:MM:SS

If :meth:`utcoffset` does not return ``None``, a 6-character string is
   appended, giving the UTC offset in (signed) hours and minutes:
   YYYY-MM-DDTHH:MM:SS.mmmmmm+HH:MM or, if :attr:`microsecond` is 0
   YYYY-MM-DDTHH:MM:SS+HH:MM

The optional argument *sep* (default ``'T'``) is a one-character separator,
   placed between the date and time portions of the result.  For example,

>>> from datetime import tzinfo, timedelta, datetime
      >>> class TZ(tzinfo):
      ...     def utcoffset(self, dt): return timedelta(minutes=-399)
      ...
      >>> datetime(2002, 12, 25, tzinfo=TZ()).isoformat(' ')
      '2002-12-25 00:00:00-06:39'

The optional argument *timespec* specifies the number of additional
   components of the time to include (the default is ``'auto'``).
   It can be one of the following:

- ``'auto'``: Same as ``'seconds'`` if :attr:`microsecond` is 0,
     same as ``'microseconds'`` otherwise.
   - ``'hours'``: Include the :attr:`hour` in the two-digit HH format.
   - ``'minutes'``: Include :attr:`hour` and :attr:`minute` in HH:MM format.
   - ``'seconds'``: Include :attr:`hour`, :attr:`minute`, and :attr:`second`
     in HH:MM:SS format.
   - ``'milliseconds'``: Include full time, but truncate fractional second
     part to milliseconds. HH:MM:SS.sss format.
   - ``'microseconds'``: Include full time in HH:MM:SS.mmmmmm format.

.. note::

Excluded time components are truncated, not rounded.

:exc:`ValueError` will be raised on an invalid *timespec* argument.

>>> from datetime import datetime
      >>> datetime.now().isoformat(timespec='minutes')
      '2002-12-25T00:00'
      >>> dt = datetime(2015, 1, 1, 12, 30, 59, 0)
      >>> dt.isoformat(timespec='microseconds')
      '2015-01-01T12:30:59.000000'

.. versionadded:: 3.6
      Added the *timespec* argument.

.. method:: datetime.__str__()

For a :class:`.datetime` instance *d*, ``str(d)`` is equivalent to
   ``d.isoformat(' ')``.

.. method:: datetime.ctime()

Return a string representing the date and time, for example ``datetime(2002, 12,
   4, 20, 30, 40).ctime() == 'Wed Dec  4 20:30:40 2002'``. ``d.ctime()`` is
   equivalent to ``time.ctime(time.mktime(d.timetuple()))`` on platforms where the
   native C :c:func:`ctime` function (which :func:`time.ctime` invokes, but which
   :meth:`datetime.ctime` does not invoke) conforms to the C standard.

.. method:: datetime.strftime(format)

Return a string representing the date and time, controlled by an explicit format
   string.  For a complete list of formatting directives, see
   :ref:`strftime-strptime-behavior`.

.. method:: datetime.__format__(format)

Same as :meth:`.datetime.strftime`.  This makes it possible to specify a format
   string for a :class:`.datetime` object in :ref:`formatted string
   literals <f-strings>` and when using :meth:`str.format`.  For a
   complete list of formatting directives, see
   :ref:`strftime-strptime-behavior`.

Examples of working with datetime objects:

.. doctest::

>>> from datetime import datetime, date, time
    >>> # Using datetime.combine()
    >>> d = date(2005, 7, 14)
    >>> t = time(12, 30)
    >>> datetime.combine(d, t)
    datetime.datetime(2005, 7, 14, 12, 30)
    >>> # Using datetime.now() or datetime.utcnow()
    >>> datetime.now()   # doctest: +SKIP
    datetime.datetime(2007, 12, 6, 16, 29, 43, 79043)   # GMT +1
    >>> datetime.utcnow()   # doctest: +SKIP
    datetime.datetime(2007, 12, 6, 15, 29, 43, 79060)
    >>> # Using datetime.strptime()
    >>> dt = datetime.strptime("21/11/06 16:30", "%d/%m/%y %H:%M")
    >>> dt
    datetime.datetime(2006, 11, 21, 16, 30)
    >>> # Using datetime.timetuple() to get tuple of all attributes
    >>> tt = dt.timetuple()
    >>> for it in tt:   # doctest: +SKIP
    ...     print(it)
    ...
    2006    # year
    11      # month
    21      # day
    16      # hour
    30      # minute
    0       # second
    1       # weekday (0 = Monday)
    325     # number of days since 1st January
    -1      # dst - method tzinfo.dst() returned None
    >>> # Date in ISO format
    >>> ic = dt.isocalendar()
    >>> for it in ic:   # doctest: +SKIP
    ...     print(it)
    ...
    2006    # ISO year
    47      # ISO week
    2       # ISO weekday
    >>> # Formatting datetime
    >>> dt.strftime("%A, %d. %B %Y %I:%M%p")
    'Tuesday, 21. November 2006 04:30PM'
    >>> 'The {1} is {0:%d}, the {2} is {0:%B}, the {3} is {0:%I:%M%p}.'.format(dt, "day", "month", "time")
    'The day is 21, the month is November, the time is 04:30PM.'

Using datetime with tzinfo:

>>> from datetime import timedelta, datetime, tzinfo
    >>> class GMT1(tzinfo):
    ...     def utcoffset(self, dt):
    ...         return timedelta(hours=1) + self.dst(dt)
    ...     def dst(self, dt):
    ...         # DST starts last Sunday in March
    ...         d = datetime(dt.year, 4, 1)   # ends last Sunday in October
    ...         self.dston = d - timedelta(days=d.weekday() + 1)
    ...         d = datetime(dt.year, 11, 1)
    ...         self.dstoff = d - timedelta(days=d.weekday() + 1)
    ...         if self.dston <=  dt.replace(tzinfo=None) < self.dstoff:
    ...             return timedelta(hours=1)
    ...         else:
    ...             return timedelta(0)
    ...     def tzname(self,dt):
    ...          return "GMT +1"
    ...
    >>> class GMT2(tzinfo):
    ...     def utcoffset(self, dt):
    ...         return timedelta(hours=2) + self.dst(dt)
    ...     def dst(self, dt):
    ...         d = datetime(dt.year, 4, 1)
    ...         self.dston = d - timedelta(days=d.weekday() + 1)
    ...         d = datetime(dt.year, 11, 1)
    ...         self.dstoff = d - timedelta(days=d.weekday() + 1)
    ...         if self.dston <=  dt.replace(tzinfo=None) < self.dstoff:
    ...             return timedelta(hours=1)
    ...         else:
    ...             return timedelta(0)
    ...     def tzname(self,dt):
    ...         return "GMT +2"
    ...
    >>> gmt1 = GMT1()
    >>> # Daylight Saving Time
    >>> dt1 = datetime(2006, 11, 21, 16, 30, tzinfo=gmt1)
    >>> dt1.dst()
    datetime.timedelta(0)
    >>> dt1.utcoffset()
    datetime.timedelta(0, 3600)
    >>> dt2 = datetime(2006, 6, 14, 13, 0, tzinfo=gmt1)
    >>> dt2.dst()
    datetime.timedelta(0, 3600)
    >>> dt2.utcoffset()
    datetime.timedelta(0, 7200)
    >>> # Convert datetime to another time zone
    >>> dt3 = dt2.astimezone(GMT2())
    >>> dt3     # doctest: +ELLIPSIS
    datetime.datetime(2006, 6, 14, 14, 0, tzinfo=<GMT2 object at 0x...>)
    >>> dt2     # doctest: +ELLIPSIS
    datetime.datetime(2006, 6, 14, 13, 0, tzinfo=<GMT1 object at 0x...>)
    >>> dt2.utctimetuple() == dt3.utctimetuple()
    True

.. _datetime-time:

:class:`.time` Objects
----------------------

A time object represents a (local) time of day, independent of any particular
day, and subject to adjustment via a :class:`tzinfo` object.

.. class:: time(hour=0, minute=0, second=0, microsecond=0, tzinfo=None, *, fold=0)

All arguments are optional.  *tzinfo* may be ``None``, or an instance of a
   :class:`tzinfo` subclass.  The remaining arguments may be integers, in the
   following ranges:

* ``0 <= hour < 24``,
   * ``0 <= minute < 60``,
   * ``0 <= second < 60``,
   * ``0 <= microsecond < 1000000``,
   * ``fold in [0, 1]``.

If an argument outside those ranges is given, :exc:`ValueError` is raised.  All
   default to ``0`` except *tzinfo*, which defaults to :const:`None`.

Class attributes:

.. attribute:: time.min

The earliest representable :class:`.time`, ``time(0, 0, 0, 0)``.

.. attribute:: time.max

The latest representable :class:`.time`, ``time(23, 59, 59, 999999)``.

.. attribute:: time.resolution

The smallest possible difference between non-equal :class:`.time` objects,
   ``timedelta(microseconds=1)``, although note that arithmetic on
   :class:`.time` objects is not supported.

Instance attributes (read-only):

.. attribute:: time.hour

In ``range(24)``.

.. attribute:: time.minute

In ``range(60)``.

.. attribute:: time.second

In ``range(60)``.

.. attribute:: time.microsecond

In ``range(1000000)``.

.. attribute:: time.tzinfo

The object passed as the tzinfo argument to the :class:`.time` constructor, or
   ``None`` if none was passed.

.. attribute:: time.fold

.. versionadded:: 3.6

Supported operations:

* comparison of :class:`.time` to :class:`.time`, where *a* is considered less
  than *b* when *a* precedes *b* in time.  If one comparand is naive and the other
  is aware, :exc:`TypeError` is raised if an order comparison is attempted. For equality
  comparisons, naive instances are never equal to aware instances.

If both comparands are aware, and have
  the same :attr:`~time.tzinfo` attribute, the common :attr:`~time.tzinfo` attribute is
  ignored and the base times are compared.  If both comparands are aware and
  have different :attr:`~time.tzinfo` attributes, the comparands are first adjusted by
  subtracting their UTC offsets (obtained from ``self.utcoffset()``). In order
  to stop mixed-type comparisons from falling back to the default comparison by
  object address, when a :class:`.time` object is compared to an object of a
  different type, :exc:`TypeError` is raised unless the comparison is ``==`` or
  ``!=``.  The latter cases return :const:`False` or :const:`True`, respectively.

.. versionchanged:: 3.3
     Equality comparisons between naive and aware :class:`~datetime.time` instances
     don't raise :exc:`TypeError`.

* hash, use as dict key

* efficient pickling

In boolean contexts, a :class:`.time` object is always considered to be true.

.. versionchanged:: 3.5
   Before Python 3.5, a :class:`.time` object was considered to be false if it
   represented midnight in UTC.  This behavior was considered obscure and
   error-prone and has been removed in Python 3.5.  See :issue:`13936` for full
   details.

Instance methods:

.. method:: time.replace(hour=self.hour, minute=self.minute, second=self.second, \
   microsecond=self.microsecond, tzinfo=self.tzinfo, * fold=0)

Return a :class:`.time` with the same value, except for those attributes given
   new values by whichever keyword arguments are specified.  Note that
   ``tzinfo=None`` can be specified to create a naive :class:`.time` from an
   aware :class:`.time`, without conversion of the time data.

.. versionadded:: 3.6
      Added the ``fold`` argument.

.. method:: time.isoformat(timespec='auto')

Return a string representing the time in ISO 8601 format, HH:MM:SS.mmmmmm or, if
   :attr:`microsecond` is 0, HH:MM:SS If :meth:`utcoffset` does not return ``None``, a
   6-character string is appended, giving the UTC offset in (signed) hours and
   minutes: HH:MM:SS.mmmmmm+HH:MM or, if self.microsecond is 0, HH:MM:SS+HH:MM

The optional argument *timespec* specifies the number of additional
   components of the time to include (the default is ``'auto'``).
   It can be one of the following:

.. note::

Excluded time components are truncated, not rounded.

:exc:`ValueError` will be raised on an invalid *timespec* argument.

>>> from datetime import time
      >>> time(hour=12, minute=34, second=56, microsecond=123456).isoformat(timespec='minutes')
      '12:34'
      >>> dt = time(hour=12, minute=34, second=56, microsecond=0)
      >>> dt.isoformat(timespec='microseconds')
      '12:34:56.000000'
      >>> dt.isoformat(timespec='auto')
      '12:34:56'

.. versionadded:: 3.6
      Added the *timespec* argument.

.. method:: time.__str__()

For a time *t*, ``str(t)`` is equivalent to ``t.isoformat()``.

.. method:: time.strftime(format)

Return a string representing the time, controlled by an explicit format
   string.  For a complete list of formatting directives, see
   :ref:`strftime-strptime-behavior`.

.. method:: time.__format__(format)

Same as :meth:`.time.strftime`. This makes it possible to specify a format string
   for a :class:`.time` object in :ref:`formatted string
   literals <f-strings>` and when using :meth:`str.format`.  For a
   complete list of formatting directives, see
   :ref:`strftime-strptime-behavior`.

.. method:: time.utcoffset()

If :attr:`.tzinfo` is ``None``, returns ``None``, else returns
   ``self.tzinfo.utcoffset(None)``, and raises an exception if the latter doesn't
   return ``None`` or a :class:`timedelta` object representing a whole number of
   minutes with magnitude less than one day.

.. method:: time.dst()

If :attr:`.tzinfo` is ``None``, returns ``None``, else returns
   ``self.tzinfo.dst(None)``, and raises an exception if the latter doesn't return
   ``None``, or a :class:`timedelta` object representing a whole number of minutes
   with magnitude less than one day.

.. method:: time.tzname()

If :attr:`.tzinfo` is ``None``, returns ``None``, else returns
   ``self.tzinfo.tzname(None)``, or raises an exception if the latter doesn't
   return ``None`` or a string object.

Example:

>>> from datetime import time, tzinfo, timedelta
    >>> class GMT1(tzinfo):
    ...     def utcoffset(self, dt):
    ...         return timedelta(hours=1)
    ...     def dst(self, dt):
    ...         return timedelta(0)
    ...     def tzname(self,dt):
    ...         return "Europe/Prague"
    ...
    >>> t = time(12, 10, 30, tzinfo=GMT1())
    >>> t                               # doctest: +ELLIPSIS
    datetime.time(12, 10, 30, tzinfo=<GMT1 object at 0x...>)
    >>> gmt = GMT1()
    >>> t.isoformat()
    '12:10:30+01:00'
    >>> t.dst()
    datetime.timedelta(0)
    >>> t.tzname()
    'Europe/Prague'
    >>> t.strftime("%H:%M:%S %Z")
    '12:10:30 Europe/Prague'
    >>> 'The {} is {:%H:%M}.'.format("time", t)
    'The time is 12:10.'

.. _datetime-tzinfo:

:class:`tzinfo` Objects
-----------------------

.. class:: tzinfo()

This is an abstract base class, meaning that this class should not be
   instantiated directly.  You need to derive a concrete subclass, and (at least)
   supply implementations of the standard :class:`tzinfo` methods needed by the
   :class:`.datetime` methods you use.  The :mod:`datetime` module supplies
   a simple concrete subclass of :class:`tzinfo`, :class:`timezone`, which can represent
   timezones with fixed offset from UTC such as UTC itself or North American EST and
   EDT.

An instance of (a concrete subclass of) :class:`tzinfo` can be passed to the
   constructors for :class:`.datetime` and :class:`.time` objects. The latter objects
   view their attributes as being in local time, and the :class:`tzinfo` object
   supports methods revealing offset of local time from UTC, the name of the time
   zone, and DST offset, all relative to a date or time object passed to them.

Special requirement for pickling:  A :class:`tzinfo` subclass must have an
   :meth:`__init__` method that can be called with no arguments, else it can be
   pickled but possibly not unpickled again.  This is a technical requirement that
   may be relaxed in the future.

A concrete subclass of :class:`tzinfo` may need to implement the following
   methods.  Exactly which methods are needed depends on the uses made of aware
   :mod:`datetime` objects.  If in doubt, simply implement all of them.

.. method:: tzinfo.utcoffset(dt)

Return offset of local time from UTC, in minutes east of UTC.  If local time is
   west of UTC, this should be negative.  Note that this is intended to be the
   total offset from UTC; for example, if a :class:`tzinfo` object represents both
   time zone and DST adjustments, :meth:`utcoffset` should return their sum.  If
   the UTC offset isn't known, return ``None``.  Else the value returned must be a
   :class:`timedelta` object specifying a whole number of minutes in the range
   -1439 to 1439 inclusive (1440 = 24\*60; the magnitude of the offset must be less
   than one day).  Most implementations of :meth:`utcoffset` will probably look
   like one of these two::

return CONSTANT                 # fixed-offset class
      return CONSTANT + self.dst(dt)  # daylight-aware class

If :meth:`utcoffset` does not return ``None``, :meth:`dst` should not return
   ``None`` either.

The default implementation of :meth:`utcoffset` raises
   :exc:`NotImplementedError`.

.. method:: tzinfo.dst(dt)

Return the daylight saving time (DST) adjustment, in minutes east of UTC, or
   ``None`` if DST information isn't known.  Return ``timedelta(0)`` if DST is not
   in effect. If DST is in effect, return the offset as a :class:`timedelta` object
   (see :meth:`utcoffset` for details). Note that DST offset, if applicable, has
   already been added to the UTC offset returned by :meth:`utcoffset`, so there's
   no need to consult :meth:`dst` unless you're interested in obtaining DST info
   separately.  For example, :meth:`datetime.timetuple` calls its :attr:`~.datetime.tzinfo`
   attribute's :meth:`dst` method to determine how the :attr:`tm_isdst` flag
   should be set, and :meth:`tzinfo.fromutc` calls :meth:`dst` to account for
   DST changes when crossing time zones.

An instance *tz* of a :class:`tzinfo` subclass that models both standard and
   daylight times must be consistent in this sense:

``tz.utcoffset(dt) - tz.dst(dt)``

must return the same result for every :class:`.datetime` *dt* with ``dt.tzinfo ==
   tz``  For sane :class:`tzinfo` subclasses, this expression yields the time
   zone's "standard offset", which should not depend on the date or the time, but
   only on geographic location.  The implementation of :meth:`datetime.astimezone`
   relies on this, but cannot detect violations; it's the programmer's
   responsibility to ensure it.  If a :class:`tzinfo` subclass cannot guarantee
   this, it may be able to override the default implementation of
   :meth:`tzinfo.fromutc` to work correctly with :meth:`astimezone` regardless.

Most implementations of :meth:`dst` will probably look like one of these two::

def dst(self, dt):
          # a fixed-offset class:  doesn't account for DST
          return timedelta(0)

or ::

def dst(self, dt):
          # Code to set dston and dstoff to the time zone's DST
          # transition times based on the input dt.year, and expressed
          # in standard local time.  Then

if dston <= dt.replace(tzinfo=None) < dstoff:
              return timedelta(hours=1)
          else:
              return timedelta(0)

The default implementation of :meth:`dst` raises :exc:`NotImplementedError`.

.. method:: tzinfo.tzname(dt)

Return the time zone name corresponding to the :class:`.datetime` object *dt*, as
   a string. Nothing about string names is defined by the :mod:`datetime` module,
   and there's no requirement that it mean anything in particular.  For example,
   "GMT", "UTC", "-500", "-5:00", "EDT", "US/Eastern", "America/New York" are all
   valid replies.  Return ``None`` if a string name isn't known.  Note that this is
   a method rather than a fixed string primarily because some :class:`tzinfo`
   subclasses will wish to return different names depending on the specific value
   of *dt* passed, especially if the :class:`tzinfo` class is accounting for
   daylight time.

The default implementation of :meth:`tzname` raises :exc:`NotImplementedError`.

These methods are called by a :class:`.datetime` or :class:`.time` object, in
response to their methods of the same names.  A :class:`.datetime` object passes
itself as the argument, and a :class:`.time` object passes ``None`` as the
argument.  A :class:`tzinfo` subclass's methods should therefore be prepared to
accept a *dt* argument of ``None``, or of class :class:`.datetime`.

When ``None`` is passed, it's up to the class designer to decide the best
response.  For example, returning ``None`` is appropriate if the class wishes to
say that time objects don't participate in the :class:`tzinfo` protocols.  It
may be more useful for ``utcoffset(None)`` to return the standard UTC offset, as
there is no other convention for discovering the standard offset.

When a :class:`.datetime` object is passed in response to a :class:`.datetime`
method, ``dt.tzinfo`` is the same object as *self*.  :class:`tzinfo` methods can
rely on this, unless user code calls :class:`tzinfo` methods directly.  The
intent is that the :class:`tzinfo` methods interpret *dt* as being in local
time, and not need worry about objects in other timezones.

There is one more :class:`tzinfo` method that a subclass may wish to override:

.. method:: tzinfo.fromutc(dt)

This is called from the default :class:`datetime.astimezone()`
   implementation.  When called from that, ``dt.tzinfo`` is *self*, and *dt*'s
   date and time data are to be viewed as expressing a UTC time.  The purpose
   of :meth:`fromutc` is to adjust the date and time data, returning an
   equivalent datetime in *self*'s local time.

Most :class:`tzinfo` subclasses should be able to inherit the default
   :meth:`fromutc` implementation without problems.  It's strong enough to handle
   fixed-offset time zones, and time zones accounting for both standard and
   daylight time, and the latter even if the DST transition times differ in
   different years.  An example of a time zone the default :meth:`fromutc`
   implementation may not handle correctly in all cases is one where the standard
   offset (from UTC) depends on the specific date and time passed, which can happen
   for political reasons. The default implementations of :meth:`astimezone` and
   :meth:`fromutc` may not produce the result you want if the result is one of the
   hours straddling the moment the standard offset changes.

Skipping code for error cases, the default :meth:`fromutc` implementation acts
   like::

def fromutc(self, dt):
          # raise ValueError error if dt.tzinfo is not self
          dtoff = dt.utcoffset()
          dtdst = dt.dst()
          # raise ValueError if dtoff is None or dtdst is None
          delta = dtoff - dtdst  # this is self's standard offset
          if delta:
              dt += delta   # convert to standard local time
              dtdst = dt.dst()
              # raise ValueError if dtdst is None
          if dtdst:
              return dt + dtdst
          else:
              return dt

Example :class:`tzinfo` classes:

.. literalinclude:: ../includes/tzinfo-examples.py

Note that there are unavoidable subtleties twice per year in a :class:`tzinfo`
subclass accounting for both standard and daylight time, at the DST transition
points.  For concreteness, consider US Eastern (UTC -0500), where EDT begins the
minute after 1:59 (EST) on the second Sunday in March, and ends the minute after
1:59 (EDT) on the first Sunday in November::

UTC   3:MM  4:MM  5:MM  6:MM  7:MM  8:MM
     EST  22:MM 23:MM  0:MM  1:MM  2:MM  3:MM
     EDT  23:MM  0:MM  1:MM  2:MM  3:MM  4:MM

start  22:MM 23:MM  0:MM  1:MM  3:MM  4:MM

end  23:MM  0:MM  1:MM  1:MM  2:MM  3:MM

When DST starts (the "start" line), the local wall clock leaps from 1:59 to
3:00.  A wall time of the form 2:MM doesn't really make sense on that day, so
``astimezone(Eastern)`` won't deliver a result with ``hour == 2`` on the day DST
begins.  For example, at the Spring forward transition of 2016, we get

>>> u0 = datetime(2016, 3, 13, 5, tzinfo=timezone.utc)
    >>> for i in range(4):
    ...     u = u0 + i*HOUR
    ...     t = u.astimezone(Eastern)
    ...     print(u.time(), 'UTC =', t.time(), t.tzname())
    ...
    05:00:00 UTC = 00:00:00 EST
    06:00:00 UTC = 01:00:00 EST
    07:00:00 UTC = 03:00:00 EDT
    08:00:00 UTC = 04:00:00 EDT

When DST ends (the "end" line), there's a potentially worse problem: there's an
hour that can't be spelled unambiguously in local wall time: the last hour of
daylight time.  In Eastern, that's times of the form 5:MM UTC on the day
daylight time ends.  The local wall clock leaps from 1:59 (daylight time) back
to 1:00 (standard time) again. Local times of the form 1:MM are ambiguous.
:meth:`astimezone` mimics the local clock's behavior by mapping two adjacent UTC
hours into the same local hour then.  In the Eastern example, UTC times of the
form 5:MM and 6:MM both map to 1:MM when converted to Eastern, but earlier times
have the :attr:`~datetime.fold` attribute set to 0 and the later times have it set to 1.
For example, at the Fall back transition of 2016, we get

>>> u0 = datetime(2016, 11, 6, 4, tzinfo=timezone.utc)
    >>> for i in range(4):
    ...     u = u0 + i*HOUR
    ...     t = u.astimezone(Eastern)
    ...     print(u.time(), 'UTC =', t.time(), t.tzname(), t.fold)
    ...
    04:00:00 UTC = 00:00:00 EDT 0
    05:00:00 UTC = 01:00:00 EDT 0
    06:00:00 UTC = 01:00:00 EST 1
    07:00:00 UTC = 02:00:00 EST 0

Note that the :class:`datetime` instances that differ only by the value of the
:attr:`~datetime.fold` attribute are considered equal in comparisons.

Applications that can't bear wall-time ambiguities should explicitly check the
value of the :attr:`~datetime.fold` attribute or avoid using hybrid
:class:`tzinfo` subclasses; there are no ambiguities when using :class:`timezone`,
or any other fixed-offset :class:`tzinfo` subclass (such as a class representing
only EST (fixed offset -5 hours), or only EDT (fixed offset -4 hours)).

.. seealso::

`dateutil.tz <https://dateutil.readthedocs.io/en/stable/tz.html>`_
      The standard library has :class:`timezone` class for handling arbitrary
      fixed offsets from UTC and :attr:`timezone.utc` as UTC timezone instance.

*dateutil.tz* library brings the *IANA timezone database* (also known as the
      Olson database) to Python and its usage is recommended.

`IANA timezone database <https://www.iana.org/time-zones>`_
      The Time Zone Database (often called tz, tzdata or zoneinfo) contains code and
      data that represent the history of local time for many representative
      locations around the globe. It is updated periodically to reflect changes
      made by political bodies to time zone boundaries, UTC offsets, and
      daylight-saving rules.

.. _datetime-timezone:

:class:`timezone` Objects
--------------------------

The :class:`timezone` class is a subclass of :class:`tzinfo`, each
instance of which represents a timezone defined by a fixed offset from
UTC.  Note that objects of this class cannot be used to represent
timezone information in the locations where different offsets are used
in different days of the year or where historical changes have been
made to civil time.

.. class:: timezone(offset, name=None)

The *offset* argument must be specified as a :class:`timedelta`
  object representing the difference between the local time and UTC.  It must
  be strictly between ``-timedelta(hours=24)`` and
  ``timedelta(hours=24)`` and represent a whole number of minutes,
  otherwise :exc:`ValueError` is raised.

The *name* argument is optional.  If specified it must be a string that
  will be used as the value returned by the :meth:`datetime.tzname` method.

.. versionadded:: 3.2

.. method:: timezone.utcoffset(dt)

Return the fixed value specified when the :class:`timezone` instance is
  constructed.  The *dt* argument is ignored.  The return value is a
  :class:`timedelta` instance equal to the difference between the
  local time and UTC.

.. method:: timezone.tzname(dt)

Return the fixed value specified when the :class:`timezone` instance
  is constructed.  If *name* is not provided in the constructor, the
  name returned by ``tzname(dt)`` is generated from the value of the
  ``offset`` as follows.  If *offset* is ``timedelta(0)``, the name
  is "UTC", otherwise it is a string 'UTC±HH:MM', where ± is the sign
  of ``offset``, HH and MM are two digits of ``offset.hours`` and
  ``offset.minutes`` respectively.

.. versionchanged:: 3.6
     Name generated from ``offset=timedelta(0)`` is now plain 'UTC', not
     'UTC+00:00'.

.. method:: timezone.dst(dt)

Always returns ``None``.

.. method:: timezone.fromutc(dt)

Return ``dt + offset``.  The *dt* argument must be an aware
  :class:`.datetime` instance, with ``tzinfo`` set to ``self``.

Class attributes:

.. attribute:: timezone.utc

The UTC timezone, ``timezone(timedelta(0))``.

.. _strftime-strptime-behavior:

:meth:`strftime` and :meth:`strptime` Behavior
----------------------------------------------

:class:`date`, :class:`.datetime`, and :class:`.time` objects all support a
``strftime(format)`` method, to create a string representing the time under the
control of an explicit format string.  Broadly speaking, ``d.strftime(fmt)``
acts like the :mod:`time` module's ``time.strftime(fmt, d.timetuple())``
although not all objects support a :meth:`timetuple` method.

Conversely, the :meth:`datetime.strptime` class method creates a
:class:`.datetime` object from a string representing a date and time and a
corresponding format string. ``datetime.strptime(date_string, format)`` is
equivalent to ``datetime(*(time.strptime(date_string, format)[0:6]))``.

For :class:`.time` objects, the format codes for year, month, and day should not
be used, as time objects have no such values.  If they're used anyway, ``1900``
is substituted for the year, and ``1`` for the month and day.

For :class:`date` objects, the format codes for hours, minutes, seconds, and
microseconds should not be used, as :class:`date` objects have no such
values.  If they're used anyway, ``0`` is substituted for them.

The full set of format codes supported varies across platforms, because Python
calls the platform C library's :func:`strftime` function, and platform
variations are common.  To see the full set of format codes supported on your
platform, consult the :manpage:`strftime(3)` documentation.

The following is a list of all the format codes that the C standard (1989
version) requires, and these work on all platforms with a standard C
implementation.  Note that the 1999 version of the C standard added additional
format codes.

+-----------+--------------------------------+------------------------+-------+
| Directive | Meaning                        | Example                | Notes |
+===========+================================+========================+=======+
| ``%a``    | Weekday as locale's            || Sun, Mon, ..., Sat    | \(1)  |
|           | abbreviated name.              |  (en_US);              |       |
|           |                                || So, Mo, ..., Sa       |       |
|           |                                |  (de_DE)               |       |
+-----------+--------------------------------+------------------------+-------+
| ``%A``    | Weekday as locale's full name. || Sunday, Monday, ...,  | \(1)  |
|           |                                |  Saturday (en_US);     |       |
|           |                                || Sonntag, Montag, ..., |       |
|           |                                |  Samstag (de_DE)       |       |
+-----------+--------------------------------+------------------------+-------+
| ``%w``    | Weekday as a decimal number,   | 0, 1, ..., 6           |       |
|           | where 0 is Sunday and 6 is     |                        |       |
|           | Saturday.                      |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%d``    | Day of the month as a          | 01, 02, ..., 31        |       |
|           | zero-padded decimal number.    |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%b``    | Month as locale's abbreviated  || Jan, Feb, ..., Dec    | \(1)  |
|           | name.                          |  (en_US);              |       |
|           |                                || Jan, Feb, ..., Dez    |       |
|           |                                |  (de_DE)               |       |
+-----------+--------------------------------+------------------------+-------+
| ``%B``    | Month as locale's full name.   || January, February,    | \(1)  |
|           |                                |  ..., December (en_US);|       |
|           |                                || Januar, Februar, ..., |       |
|           |                                |  Dezember (de_DE)      |       |
+-----------+--------------------------------+------------------------+-------+
| ``%m``    | Month as a zero-padded         | 01, 02, ..., 12        |       |
|           | decimal number.                |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%y``    | Year without century as a      | 00, 01, ..., 99        |       |
|           | zero-padded decimal number.    |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%Y``    | Year with century as a decimal | 0001, 0002, ..., 2013, | \(2)  |
|           | number.                        | 2014, ..., 9998, 9999  |       |
+-----------+--------------------------------+------------------------+-------+
| ``%H``    | Hour (24-hour clock) as a      | 00, 01, ..., 23        |       |
|           | zero-padded decimal number.    |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%I``    | Hour (12-hour clock) as a      | 01, 02, ..., 12        |       |
|           | zero-padded decimal number.    |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%p``    | Locale's equivalent of either  || AM, PM (en_US);       | \(1), |
|           | AM or PM.                      || am, pm (de_DE)        | \(3)  |
+-----------+--------------------------------+------------------------+-------+
| ``%M``    | Minute as a zero-padded        | 00, 01, ..., 59        |       |
|           | decimal number.                |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%S``    | Second as a zero-padded        | 00, 01, ..., 59        | \(4)  |
|           | decimal number.                |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%f``    | Microsecond as a decimal       | 000000, 000001, ...,   | \(5)  |
|           | number, zero-padded on the     | 999999                 |       |
|           | left.                          |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%z``    | UTC offset in the form +HHMM   | (empty), +0000, -0400, | \(6)  |
|           | or -HHMM (empty string if the  | +1030                  |       |
|           | object is naive).              |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%Z``    | Time zone name (empty string   | (empty), UTC, EST, CST |       |
|           | if the object is naive).       |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%j``    | Day of the year as a           | 001, 002, ..., 366     |       |
|           | zero-padded decimal number.    |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%U``    | Week number of the year        | 00, 01, ..., 53        | \(7)  |
|           | (Sunday as the first day of    |                        |       |
|           | the week) as a zero padded     |                        |       |
|           | decimal number. All days in a  |                        |       |
|           | new year preceding the first   |                        |       |
|           | Sunday are considered to be in |                        |       |
|           | week 0.                        |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%W``    | Week number of the year        | 00, 01, ..., 53        | \(7)  |
|           | (Monday as the first day of    |                        |       |
|           | the week) as a decimal number. |                        |       |
|           | All days in a new year         |                        |       |
|           | preceding the first Monday     |                        |       |
|           | are considered to be in        |                        |       |
|           | week 0.                        |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%c``    | Locale's appropriate date and  || Tue Aug 16 21:30:00   | \(1)  |
|           | time representation.           |  1988 (en_US);         |       |
|           |                                || Di 16 Aug 21:30:00    |       |
|           |                                |  1988 (de_DE)          |       |
+-----------+--------------------------------+------------------------+-------+
| ``%x``    | Locale's appropriate date      || 08/16/88 (None);      | \(1)  |
|           | representation.                || 08/16/1988 (en_US);   |       |
|           |                                || 16.08.1988 (de_DE)    |       |
+-----------+--------------------------------+------------------------+-------+
| ``%X``    | Locale's appropriate time      || 21:30:00 (en_US);     | \(1)  |
|           | representation.                || 21:30:00 (de_DE)      |       |
+-----------+--------------------------------+------------------------+-------+
| ``%%``    | A literal ``'%'`` character.   | %                      |       |
+-----------+--------------------------------+------------------------+-------+

Several additional directives not required by the C89 standard are included for
convenience. These parameters all correspond to ISO 8601 date values. These
may not be available on all platforms when used with the :meth:`strftime`
method. The ISO 8601 year and ISO 8601 week directives are not interchangeable
with the year and week number directives above. Calling :meth:`strptime` with
incomplete or ambiguous ISO 8601 directives will raise a :exc:`ValueError`.

+-----------+--------------------------------+------------------------+-------+
| Directive | Meaning                        | Example                | Notes |
+===========+================================+========================+=======+
| ``%G``    | ISO 8601 year with century     | 0001, 0002, ..., 2013, | \(8)  |
|           | representing the year that     | 2014, ..., 9998, 9999  |       |
|           | contains the greater part of   |                        |       |
|           | the ISO week (``%V``).         |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%u``    | ISO 8601 weekday as a decimal  | 1, 2, ..., 7           |       |
|           | number where 1 is Monday.      |                        |       |
+-----------+--------------------------------+------------------------+-------+
| ``%V``    | ISO 8601 week as a decimal     | 01, 02, ..., 53        | \(8)  |
|           | number with Monday as          |                        |       |
|           | the first day of the week.     |                        |       |
|           | Week 01 is the week containing |                        |       |
|           | Jan 4.                         |                        |       |
+-----------+--------------------------------+------------------------+-------+

.. versionadded:: 3.6
   ``%G``, ``%u`` and ``%V`` were added.

Notes:

(1)
   Because the format depends on the current locale, care should be taken when
   making assumptions about the output value. Field orderings will vary (for
   example, "month/day/year" versus "day/month/year"), and the output may
   contain Unicode characters encoded using the locale's default encoding (for
   example, if the current locale is ``ja_JP``, the default encoding could be
   any one of ``eucJP``, ``SJIS``, or ``utf-8``; use :meth:`locale.getlocale`
   to determine the current locale's encoding).

(2)
   The :meth:`strptime` method can parse years in the full [1, 9999] range, but
   years < 1000 must be zero-filled to 4-digit width.

.. versionchanged:: 3.2
      In previous versions, :meth:`strftime` method was restricted to
      years >= 1900.

.. versionchanged:: 3.3
      In version 3.2, :meth:`strftime` method was restricted to
      years >= 1000.

(3)
   When used with the :meth:`strptime` method, the ``%p`` directive only affects
   the output hour field if the ``%I`` directive is used to parse the hour.

(4)
   Unlike the :mod:`time` module, the :mod:`datetime` module does not support
   leap seconds.

(5)
   When used with the :meth:`strptime` method, the ``%f`` directive
   accepts from one to six digits and zero pads on the right.  ``%f`` is
   an extension to the set of format characters in the C standard (but
   implemented separately in datetime objects, and therefore always
   available).

(6)
   For a naive object, the ``%z`` and ``%Z`` format codes are replaced by empty
   strings.

For an aware object:

``%z``
      :meth:`utcoffset` is transformed into a 5-character string of the form
      +HHMM or -HHMM, where HH is a 2-digit string giving the number of UTC
      offset hours, and MM is a 2-digit string giving the number of UTC offset
      minutes.  For example, if :meth:`utcoffset` returns
      ``timedelta(hours=-3, minutes=-30)``, ``%z`` is replaced with the string
      ``'-0330'``.

``%Z``
      If :meth:`tzname` returns ``None``, ``%Z`` is replaced by an empty
      string.  Otherwise ``%Z`` is replaced by the returned value, which must
      be a string.

.. versionchanged:: 3.2
      When the ``%z`` directive is provided to the :meth:`strptime` method, an
      aware :class:`.datetime` object will be produced.  The ``tzinfo`` of the
      result will be set to a :class:`timezone` instance.

(7)
   When used with the :meth:`strptime` method, ``%U`` and ``%W`` are only used
   in calculations when the day of the week and the calendar year (``%Y``)
   are specified.

(8)
   Similar to ``%U`` and ``%W``, ``%V`` is only used in calculations when the
   day of the week and the ISO year (``%G``) are specified in a
   :meth:`strptime` format string. Also note that ``%G`` and ``%Y`` are not
   interchangeable.

.. rubric:: Footnotes

.. [#] If, that is, we ignore the effects of Relativity

cmd: