def to_timestamp(dt_str, tz_str):

    dt = datetime.strptime(dt_str, '%Y-%m-%d %H:%M:%S')

    tz_re_match = re.match(

        r'^UTC(\+|\-)(0[0-9]|1[0-9]|2[0-3]|[0-9])\:(0[0-9]|1[0-9]|2[0-9]|3[0-9]|4[0-9]|5[0-9]|[0-9])$',

        tz_str)

    tz_hours_int = int(tz_re_match.group(1) + tz_re_match.group(2))

    tz_minutes_int = int(tz_re_match.group(3))

    tz = timezone(timedelta(hours=tz_hours_int, minutes=tz_minutes_int))

    dt = dt.replace(tzinfo=tz)

    return dt.timestamp()