def test_agentGetPublicKey(self):
        """
        L{SSHUserAuthClient} looks up public keys from the agent using the
        L{SSHAgentClient} class.  That L{SSHAgentClient.getPublicKey} returns a
        L{Key} object with one of the public keys in the agent.  If no more
        keys are present, it returns L{None}.
        """
        agent = SSHAgentClient()
        agent.blobs = [self.rsaPublic.blob()]
        key = agent.getPublicKey()
        self.assertTrue(key.isPublic())
        self.assertEqual(key, self.rsaPublic)
        self.assertIsNone(agent.getPublicKey())

        L{SSHUserAuthClient} looks up public keys from the agent using the
        L{SSHAgentClient} class.  That L{SSHAgentClient.getPublicKey} returns a
        L{Key} object with one of the public keys in the agent.  If no more
        keys are present, it returns L{None}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_default.py