'Test that a coroutine returning a value is substituted with the that
value when flattened.'

def test_serializeCoroutine(self):

    from textwrap import dedent
    namespace = {}
    exec dedent('\n                                                async    def    coro(x):\n                                                                return    x\n                                                ') in namespace
    coro = namespace['coro']
    return self.assertFlattensTo(coro('four'), 'four')
