'H')
    DatetimeIndex(['2018-01-01 11:00:00', '2018-01-01 12:00:00',
                   '2018-01-01 12:00:00'],
                  dtype='datetime64[ns]', freq=None)

    **Series**

    >>> pd.Series(rng).dt.floor("H")
    0   2018-01-01 11:00:00
    1   2018-01-01 12:00:00
    2   2018-01-01 12:00:00
    dtype: datetime64[ns]

    When rounding near a daylight savings time transition, use ``ambiguous`` or
    ``nonexistent`` to control how the timestamp should be re-localized.

    >>> rng_tz = pd.DatetimeIndex(["2021-10-31 03:30:00"], tz="Europe/Amsterdam")

    >>> rng_tz.floor("2H", ambiguous=False)
    DatetimeIndex(['2021-10-31 02:00:00+01:00'],
                 dtype='datetime64[ns, Europe/Amsterdam]', freq=None)

    >>> rng_tz.floor("2H", ambiguous=True)
    DatetimeIndex(['2021-10-31 02:00:00+02:00'],
                  dtype='datetime64[ns, Europe/Amsterdam]', freq=None)
    aŚ