def test_str(self):
        """
        The string representation of a L{DelayedCall} instance, as returned by
        L{str}, includes the unsigned id of the instance, as well as its state,
        the function to be called, and the function arguments.
        """
        dc = DelayedCall(12, nothing, (3, ), {"A": 5}, None, None, lambda: 1.5)
        expected = (
            "<DelayedCall 0x{:x} [10.5s] called=0 cancelled=0 "
            "nothing(3, A=5)>".format(id(dc)))
        self.assertEqual(str(dc), expected)

        The string representation of a L{DelayedCall} instance, as returned by
        L{str}, includes the unsigned id of the instance, as well as its state,
        the function to be called, and the function arguments.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_base.py