def test_verifyOKKey(self):
        """
        L{default.verifyHostKey} should return a L{Deferred} which fires with
        C{1} when passed a host, IP, and key which already match the
        known_hosts file it is supposed to check.
        """
        l = []
        default.verifyHostKey(self.fakeTransport, b"4.3.2.1", sampleKey,
                              b"I don't care.").addCallback(l.append)
        self.assertEqual([1], l)

        L{default.verifyHostKey} should return a L{Deferred} which fires with
        C{1} when passed a host, IP, and key which already match the
        known_hosts file it is supposed to check.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_knownhosts.py