ype for timezone-aware datetime data.

    **This is not an actual numpy dtype**, but a duck type.

    Parameters
    ----------
    unit : str, default "ns"
        The precision of the datetime data. Currently limited
        to ``"ns"``.
    tz : str, int, or datetime.tzinfo
        The timezone.

    Attributes
    ----------
    unit
    tz

    Methods
    -------
    None

    Raises
    ------
    pytz.UnknownTimeZoneError
        When the requested timezone cannot be found.

    Examples
    --------
    >>> pd.DatetimeTZDtype(tz='UTC')
    datetime64[ns, UTC]

    >>> pd.DatetimeTZDtype(tz='dateutil/US/Central')
    datetime64[ns, tzfile('/usr/share/zoneinfo/US/Central')]
    ztype[Timestamp]r+