def test_helloFatalErrorHandling(self):
        """
        Verify that if a known, fatal error type is raised and handled, it will
        be properly relayed to the other end of the connection and translated
        into an exception, no error will be logged, and the connection will be
        terminated.
        """
        L=[]
        c, s, p = connectedServerAndClient(
            ServerClass=SimpleSymmetricCommandProtocol,
            ClientClass=SimpleSymmetricCommandProtocol)
        HELLO = b'die'
        c.sendHello(HELLO).addErrback(L.append)
        p.flush()
        L.pop().trap(DeathThreat)
        c.sendHello(HELLO).addErrback(L.append)
        p.flush()
        L.pop().trap(error.ConnectionDone)

        Verify that if a known, fatal error type is raised and handled, it will
        be properly relayed to the other end of the connection and translated
        into an exception, no error will be logged, and the connection will be
        terminated.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_amp.py