misc: label descent

label descent:
    description:
        label descent
        the idea is to define operators that can act on whole categories of objects
        instead of being defined with respect to a single specific ket
        the most common use cases are: |some category: *> and |*>
        |some category: *> is used to define operators with respect to only kets with the category "some category"
        while |*> is used to define operators with respect to all kets
        noting that operators defined with respect to |*> have lower precedence than operators defined with respect to a specific ket
        allowing us to define specific rules that over-write and have higher precedence than general rules

    examples:
        -- just a toy example:
        is-food |food: *> => |yes>
        is-food |*> => |no>

        -- now invoke it:
        is-food |food: bread>
            |yes>

        is-food |Fred Smith>
            |no>

    see also:
        |*>, |_self>