ket fn: ceiling

ceiling:
    description:
        ceiling ket
        take the ceiling function of the value in the ket label
        while preserving the ket label category
        if the value is not a number, then return the ket unchanged
        also, we preserve the ket coefficient

    examples:
        -- ceiling of a simple number:
        ceiling |2.7>
            |3>

        -- ceiling of a number with a category, in this case "number"
        ceiling |number: 5.3>
            |number: 6>

        -- attempted ceiling of a non number:
        ceiling |alpha>
            |alpha>

    see also:
        floor, log