def test_findFailureInGenerator(self):
        """
        Within an exception handler, it should be possible to find the
        original Failure that caused the current exception (if it was
        caused by throwExceptionIntoGenerator).
        """
        f = getDivisionFailure()
        f.cleanFailure()

        foundFailures = []
        def generator():
            try:
                yield
            except:
                foundFailures.append(failure.Failure._findFailure())
            else:
                self.fail("No exception sent to generator")

        g = generator()
        next(g)
        self._throwIntoGenerator(f, g)

        self.assertEqual(foundFailures, [f])

        Within an exception handler, it should be possible to find the
        original Failure that caused the current exception (if it was
        caused by throwExceptionIntoGenerator).
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_failure.py