def add_hierarchy(self, parent, edge, child):  # XXX DEPRECATED
        """ Helper function to simplify the addition of part_of style
            objectProperties to graphs. FIXME make a method of makeGraph?
        """
        if type(parent) != rdflib.URIRef:
            parent = self.check_thing(parent)

        if type(edge) != rdflib.URIRef:
            edge = self.check_thing(edge)

        if type(child) != infixowl.Class:
            if type(child) != rdflib.URIRef:
                child = self.check_thing(child)
            child = infixowl.Class(child, graph=self.g)

        restriction = infixowl.Restriction(edge, graph=self.g, someValuesFrom=parent)
        child.subClassOf = [restriction] + [c for c in child.subClassOf]
Helper function to simplify the addition of part_of style
            objectProperties to graphs. FIXME make a method of makeGraph?