        with day first.

    yearfirst : bool, default False
        Specify a date parse order if `arg` is str or is list-like.

        - If :const:`True` parses dates with the year first, e.g.
          :const:`"10/11/12"` is parsed as :const:`2010-11-12`.
        - If both `dayfirst` and `yearfirst` are :const:`True`, `yearfirst` is
          preceded (same as :mod:`dateutil`).

        .. warning::

            ``yearfirst=True`` is not strict, but will prefer to parse
            with year first.

    utc : bool, default False
        Control timezone-related parsing, localization and conversion.

        - If :const:`True`, the function *always* returns a timezone-aware
          UTC-localized :class:`Timestamp`, :class:`Series` or
          :class:`DatetimeIndex`. To do this, timezone-naive inputs are
          *localized* as UTC, while timezone-aware inputs are *converted* to UTC.

        - If :const:`False` (default), inputs will not be coerced to UTC.
          Timezone-naive inputs will remain naive, while timezone-aware ones
          will keep their time offsets. Limitations exist for mixed
          offsets (typically, daylight savings), see :ref:`Examples
          <to_datetime_tz_examples>` section for details.

        .. warning::

            In a future version of pandas, parsing datetimes with mixed time
            zones will raise an error unless `utc=True`.
            Please specify `utc=True` to opt in to the new behaviour
            and silence this warning. To create a `Series` with mixed offsets and
            `object` dtype, please use `apply` and `datetime.datetime.strptime`.

        See also: pandas general documentation about `timezone conversion and
        localization
        <https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html
        #time-zone-handling>`_.

    format : str, default None
        The strftime to parse time, e.g. :const:`"%d/%m/%Y"`. See
        `strftime documentation
        <https://docs.python.org/3/library/datetime.html
        #strftime-and-strptime-behavior>`_ for more information on choices, though
        note that :const:`"%f"` will parse all the way up to nanoseconds.
        You can also pass:

        - "ISO8601", to parse any `ISO8601 <https://en.wikipedia.org/wiki/ISO_8601>`_
          time string (not necessarily in exactly the same format);
        - "mixed", to infer the format for each element individually. This is risky,
          and you should probably use it along with `dayfirst`.

        .. note::

            If a :class:`DataFrame` is passed, then `format` has no effect.

    exact : bool, default True
        Control how `format` is used:

        - If :const:`True`, require an exact `format` match.
        - If :const:`False`, allow the `format` to match anywhere in the target
          string.

        Cannot be used alongside ``format='ISO8601'`` or ``format='mixed'``.
    unit : str, default 'ns'
        The unit of the arg (D,s,ms,us,ns) denote the unit, which is an
        integer or float number. This will be based off the origin.
        Example, with ``unit='ms'`` and ``origin='unix'``, this would calculate
        the number of milliseconds to the unix epoch start.
    infer_datetime_format : bool, default False
        If :const:`True` and no `format` is given, attempt to infer the format
        of the datetime strings based on the first non-NaN element,
        and if it can be inferred, switch to a faster method of parsing them.
        In some cases this can increase the parsing speed by ~5-10x.

        .. deprecated:: 2.0.0
            A strict version of this argument is now the default, passing it has
            no effect.

    origin : scalar, default 'unix'
        Define the reference date. The numeric values would be parsed as number
        of units (defined by `unit`) since this reference date.

        - If :const:`'unix'` (or POSIX) time; origin is set to 1970-01-01.
        - If :const:`'julian'`, unit must be :const:`'D'`, and origin is set to
          beginning of Julian Calendar. Julian day number :const:`0` is assigned
          to the day starting at noon on January 1, 4713 BC.
        - If Timestamp convertible (Timestamp, dt.datetime, np.datetimt64 or date
          string), origin is set to Timestamp identified by origin.
        - If a float or integer, origin is the millisecond difference
          relative to 1970-01-01.
    cache : bool, default True
        If :const:`True`, use a cache of unique, converted dates to apply the
        datetime conversion. May produce significant speed-up when parsing
        duplicate date strings, especially ones with timezone offsets. The cache
        is only used when there are at least 50 values. The presence of
        out-of-bounds values will render the cache unusable and may slow down
        parsing.

    Returns
    -------
    datetime
        If parsing succeeded.
        Return type depends on input (types in parenthesis correspond to
        fallback in case of unsuccessful timezone or out-of-range timestamp
        parsing):

        - scalar: :class:`Timestamp` (or :class:`datetime.datetime`)
        - array-like: :class:`DatetimeIndex` (or :class:`Series` with
          :class:`object` dtype containing :class:`datetime.datetime`)
        - Series: :class:`Series` of :class:`datetime64` dtype (or
          :class:`Series` of :class:`object` dtype containing
          :class:`datetime.datetime`)
        - DataFrame: :class:`Series` of :class:`datetime64` dtype (or
          :class:`Series` of :class:`object` dtype containing
          :class:`datetime.datetime`)

    Raises
    ------
    ParserError
        When parsing a date from string fails.
    ValueError
        When another datetime conversion error happens. For example when one
        of 'year', 'month', day' columns is missing in a :class:`DataFrame`, or
        when a Timezone-aware :class:`datetime.datetime` is found in an array-like
        of mixed time offsets, and ``utc=False``.

    See Also
    --------
    DataFrame.astype : Cast argument to a specified dtype.
    to_timedelta : Convert argument to timedelta.
    convert_dtypes : Convert dtypes.

    Notes
    -----

    Many input types are supported, and lead to different output types:

    - **scalars** can be int, float, str, datetime object (from stdlib :mod:`datetime`
      module or :mod:`numpy`). They are converted to :class:`Timestamp` when
      possible, otherwise they are converted to :class:`datetime.datetime`.
      None/NaN/null scalars are converted to :const:`NaT`.

    - **array-like** can contain int, float, str, datetime objects. They are
      converted to :class:`DatetimeIndex` when possible, otherwise they are
      converted to :class:`Index` with :class:`object` dtype, containing
      :class:`datetime.datetime`. None/NaN/null entries are converted to
      :const:`NaT` in both cases.

    - **Series** are converted to :class:`Series` with :class:`datetime64`
      dtype when possible, otherwise they are converted to :class:`Series` with
      :class:`object` dtype, containing :class:`datetime.datetime`. None/NaN/null
      entries are converted to :const:`NaT` in both cases.

    - **DataFrame/dict-like** are converted to :class:`Series` with
      :class:`datetime64` dtype. For each row a datetime is created from assembling
      the various dataframe columns. Column keys can be common abbreviations
      like ['year', 'month', 'day', 'minute', 'second', 'ms', 'us', 'ns']) or
      plurals of the same.

    The following causes are responsible for :class:`datetime.datetime` objects
    being returned (possibly inside an :class:`Index` or a :class:`Series` with
    :class:`object` dtype) instead of a proper pandas designated type
    (:class:`Timestamp`, :class:`DatetimeIndex` or :class:`Series`
    with :class:`datetime64` dtype):

    - when any input element is before :const:`Timestamp.min` or after
      :const:`Timestamp.max`, see `timestamp limitations
      <https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html
      #timeseries-timestamp-limits>`_.

    - when ``utc=False`` (default) and the input is an array-like or
      :class:`Series` containing mixed naive/aware datetime, or aware with mixed
      time offsets. Note that this happens in the (quite frequent) situation when
      the timezone has a daylight savings policy. In that case you may wish to
      use ``utc=True``.

    Examples
    --------

    **Handling various input formats**

    Assembling a datetime from multiple columns of a :class:`DataFrame`. The keys
    can be common abbreviations like ['year', 'month', 'day', 'minute', 'second',
    'ms', 'us', 'ns']) or plurals of the same

    >>> df = pd.DataFrame({'year': [2015, 2016],
    ...                    'month': [2, 3],
    ...                    'day': [4, 5]})
    >>> pd.to_datetime(df)
    0   2015-02-04
    1   2016-03-05
    dtype: datetime64[ns]

    Using a unix epoch time

    >>> pd.to_datetime(1490195805, unit='s')
    Timestamp('2017-03-22 15:16:45')
    >>> pd.to_datetime(1490195805433502912, unit='ns')
    Timestamp('2017-03-22 15:16:45.433502912')

    .. warning:: For float arg, precision rounding might happen. To prevent
        unexpected behavior use a fixed-width exact type.

    Using a non-unix epoch origin

    >>> pd.to_datetime([1, 2, 3], unit='D',
    ...                origin=pd.Timestamp('1960-01-01'))
    DatetimeIndex(['1960-01-02', '1960-01-03', '1960-01-04'],
                  dtype='datetime64[ns]', freq=None)

    **Differences with strptime behavior**

    :const:`"%f"` will parse all the way up to nanoseconds.

    >>> pd.to_datetime('2018-10-26 12:00:00.0000000011',
    ...                format='%Y-%m-%d %H:%M:%S.%f')
    Timestamp('2018-10-26 12:00:00.000000001')

    **Non-convertible date/times**

    If a date does not meet the `timestamp limitations
    <https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html
    #timeseries-timestamp-limits>`_, passing ``errors='ignore'``
    will return the original input instead of raising any exception.

    Passing ``errors='coerce'`` will force an out-of-bounds date to :const:`NaT`,
    in addition to forcing non-dates (or non-parseable dates) to :const:`NaT`.

    >>> pd.to_datetime('13000101', format='%Y%m%d', errors='ignore')
    '13000101'
    >>> pd.to_datetime('13000101', format='%Y%m%d', errors='coerce')
    NaT

    .. _to_datetime_tz_examples:

    **Timezones and time offsets**

    The default behaviour (``utc=False``) is as follows:

    - Timezone-naive inputs are converted to timezone-naive :class:`DatetimeIndex`:

    >>> pd.to_datetime(['2018-10-26 12:00:00', '2018-10-26 13:00:15'])
    DatetimeIndex(['2018-10-26 12:00:00', '2018-10-26 13:00:15'],
                  dtype='datetime64[ns]', freq=None)

    - Timezone-aware inputs *with constant time offset* are converted to
      timezone-aware :class:`DatetimeIndex`:

    >>> pd.to_datetime(['2018-10-26 12:00 -0500', '2018-10-26 13:00 -0500'])
    DatetimeIndex(['2018-10-26 12:00:00-05:00', '2018-10-26 13:00:00-05:00'],
                  dtype='datetime64[ns, UTC-05:00]', freq=None)

    - However, timezone-aware inputs *with mixed time offsets* (for example
      issued from a timezone with daylight savings, such as Europe/Paris)
      are **not successfully converted** to a :class:`DatetimeIndex`.
      Parsing datetimes with mixed time zones will show a warning unless
      `utc=True`. If you specify `utc=False` the warning below will be shown
      and a simple :class:`Index` containing :class:`datetime.datetime`
      objects will be returned:

    >>> pd.to_datetime(['2020-10-25 02:00 +0200',
    ...                 '2020-10-25 04:00 +0100'])  # doctest: +SKIP
    FutureWarning: In a future version of pandas, parsing datetimes with mixed
    time zones will raise an error unless `utc=True`. Please specify `utc=True`
    to opt in to the new behaviour and silence this warning. To create a `Series`
    with mixed offsets and `object` dtype, please use `apply` and
    `datetime.datetime.strptime`.
    Index([2020-10-25 02:00:00+02:00, 2020-10-25 04:00:00+01:00],
          dtype='object')

    - A mix of timezone-aware and timezone-naive inputs is also converted to
      a simple :class:`Index` containing :class:`datetime.datetime` objects:

    >>> from datetime import datetime
    >>> pd.to_datetime(["2020-01-01 01:00:00-01:00",
    ...                 datetime(2020, 1, 1, 3, 0)])  # doctest: +SKIP
    FutureWarning: In a future version of pandas, parsing datetimes with mixed
    time zones will raise an error unless `utc=True`. Please specify `utc=True`
    to opt in to the new behaviour and silence this warning. To create a `Series`
    with mixed offsets and `object` dtype, please use `apply` and
    `datetime.datetime.strptime`.
    Index([2020-01-01 01:00:00-01:00, 2020-01-01 03:00:00], dtype='object')

    |

    Setting ``utc=True`` solves most of the above issues:

    - Timezone-naive inputs are *localized* as UTC

    >>> pd.to_datetime(['2018-10-26 12:00', '2018-10-26 13:00'], utc=True)
    DatetimeIndex(['2018-10-26 12:00:00+00:00', '2018-10-26 13:00:00+00:00'],
                  dtype='datetime64[ns, UTC]', freq=None)

    - Timezone-aware inputs are *converted* to UTC (the output represents the
      exact same datetime, but viewed from the UTC time offset `+00:00`).

    >>> pd.to_datetime(['2018-10-26 12:00 -0530', '2018-10-26 12:00 -0500'],
    ...                utc=True)
    DatetimeIndex(['2018-10-26 17:30:00+00:00', '2018-10-26 17:00:00+00:00'],
                  dtype='datetime64[ns, UTC]', freq=None)

    - Inputs can contain both string or datetime, the above
      rules still apply

    >>> pd.to_datetime(['2018-10-26 12:00', datetime(2020, 1, 1, 18)], utc=True)
    DatetimeIndex(['2018-10-26 12:00:00+00:00', '2020-01-01 18:00:00+00:00'],
                  dtype='datetime64[ns, UTC]', freq=None)
    >