ket fn: ket-length

ket-length:
    description:
        ket-length input-seq
        Maps each ket in input-seq to its size

    examples:
        ket-length (|apple> + |orange> + |fish>)
            |number: 5> + |number: 6> + |number: 4>

    see also:
        how-many, show-many, sort-by