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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def verifyStubbedInvocationsAreUsed(*objs):
 """Ensure stubs are actually used. This functions just ensures that stubbed methods are actually used. Its purpose is to detect interface changes after refactorings. It is meant to be invoked usually without arguments just before :func:`unstub`. """

    if objs:
        theMocks = map(_get_mock_or_raise, objs)
    else:
        theMocks = mock_registry.get_registered_mocks()


    for mock in theMocks:
        for i in mock.stubbed_invocations:
            if not i.allow_zero_invocations and i.used < len(i.answers):
                raise VerificationError("\nUnused stub: %s" % i)