:rc:`date.epoch` or `.set_epoch`.
    tz : str or `~datetime.tzinfo`, default: :rc:`timezone`
        Timezone of *x*. If a string, *tz* is passed to `dateutil.tz`.

    Returns
    -------
    `~datetime.datetime` or sequence of `~datetime.datetime`
        Dates are returned in timezone *tz*.

        If *x* is a sequence, a sequence of `~datetime.datetime` objects will
        be returned.

    Notes
    -----
    The Gregorian calendar is assumed; this is not universal practice.
    For details, see the module docstring.
    )