::date [OPTION]... [+FORMAT] {
    match FORMAT {
        "+%s" {
            <1 : TimePoint
                 ~<TimeSince UnixEpoch>
                 ~<Duration Seconds>
                 ~ℕ
                 ~<PosInt 10 BigEndian>
                 ~<Seq <Digit 10>~Char>
        }
        * {
            <1 : TimePoint ;
        }
    }
}