def test_empty(self):
        """
        The repr of an empty angle says that is of unknown type and unknown
        value.
        """
        a = base.Angle()
        self.assertEqual("<Angle of unknown type (unknown value)>", repr(a))

        The repr of an empty angle says that is of unknown type and unknown
        value.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/positioning/test/test_base.py