compound context seq fn: inherit-path

inherit-path:
    description:
        inherit-path[parent-type] input-seq
        return the inherit path for the kets in input-seq

    examples:
        -- learn some inheritance paths:
        parent-type |trudy> => |cat>
        parent-type |cat> => |feline>
        parent-type |feline> => |mammal>
        parent-type |mammal> => |animal>

        parent-type |rex> => |dog>
        parent-type |dog> => |canine>
        parent-type |canine> => |mammal>

        -- now find the inheritance path for trudy and rex:
        inherit-path[parent-type] (|trudy> + |rex>)
            |animal: mammal: feline: cat: trudy> + |animal: mammal: canine: dog: rex>

    see also:
        inherit, extract-value, extract-category