def test_is_subscribed_exist(ed):
    listener = lambda x: x
    ed.subscribe("T1", listener, lambda x: True)
    assert True is ed.is_subscribed("T1", listener)
def test_is_subscribed_not_listener(ed):
    listener = lambda x: x
    ed.subscribe("T1", listener, lambda x: True)
    assert False is ed.is_subscribed("T1", lambda y: y)
def test_is_subscribed_not_topic(ed):
    assert False is ed.is_subscribed("T1", lambda x: x)