def test_expunge(self):
        """
        L{IMAP4Client.expunge} sends the I{EXPUNGE} command and returns a
        L{Deferred} which fires with a C{list} of message sequence numbers
        given by the server's response.
        """
        d = self._expunge()
        self._response([3, 3, 5, 8])
        self.assertEqual(self.successResultOf(d), [3, 3, 5, 8])

        L{IMAP4Client.expunge} sends the I{EXPUNGE} command and returns a
        L{Deferred} which fires with a C{list} of message sequence numbers
        given by the server's response.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/test/test_imap.py