If is_a_type is a derivable type, check whether type is a descendant of is_a_type. If is_a_type is an interface, check whether type conforms to it.
type to check anchestry for
possible anchestor of type or interface that type could conform to
TRUE if type is a is_a_type
If is_a_type is a derivable type, check whether type is a descendant of is_a_type. If is_a_type is an interface, check whether type conforms to it.