def test_copySequenceNumbers(self):
        """
        L{IMAP4Client.copy} copies the messages identified by their
        sequence numbers to the mailbox, returning a L{Deferred} that
        succeeds with a true value.
        """
        d = self.client.copy("2:3", "MEETING", uid=False)

        self.assertEqual(
            self.transport.value(),
            b"0001 COPY 2:3 MEETING\r\n",
        )

        self.client.lineReceived(b"0001 OK COPY completed")
        self.assertEqual(self.successResultOf(d),
                         ([], b'OK COPY completed'))

        L{IMAP4Client.copy} copies the messages identified by their
        sequence numbers to the mailbox, returning a L{Deferred} that
        succeeds with a true value.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/test/test_imap.py