Convert a UTC datetime to datetime in local timezone

def utc_dt_to_local_dt(dtm):
    """Convert a UTC datetime to datetime in local timezone"""
    utc_zone = mktz("UTC")
    if dtm.tzinfo is not None and dtm.tzinfo != utc_zone:
        raise ValueError(
            "Expected dtm without tzinfo or with UTC, not %r" % (
                dtm.tzinfo
            )
        )

    if dtm.tzinfo is None:
        dtm = dtm.replace(tzinfo=utc_zone)
    return dtm.astimezone(mktz())