def METHOD_NAME(create, element_factory):
    gen = create(GeneralizationItem)
    c1 = create(ClassItem, UML.Class)
    c2 = create(ClassItem, UML.Class)
    connect(gen, gen.head, c1)
    connect(gen, gen.tail, c2)
    # Now do the same on a new diagram:
    diagram2 = element_factory.create(Diagram)
    c3 = diagram2.create(ClassItem, subject=c1.subject)
    c4 = diagram2.create(ClassItem, subject=c2.subject)
    gen2 = diagram2.create(GeneralizationItem)
    connect(gen2, gen2.head, c3)
    connect(gen2, gen2.tail, c4)
    assert gen.subject is gen2.subject