Adds @prerequisite_type to the list of prerequisites of @interface_type.
This means that any type implementing @interface_type must also implement
@prerequisite_type. Prerequisites can be thought of as an alternative to
interface derivation (which GType doesn't support). An interface can have
at most one instantiatable prerequisite type.
Adds @prerequisite_type to the list of prerequisites of @interface_type. This means that any type implementing @interface_type must also implement @prerequisite_type. Prerequisites can be thought of as an alternative to interface derivation (which GType doesn't support). An interface can have at most one instantiatable prerequisite type.