def test_fetchSpecificNumbered(self):
        """
        L{IMAP4Client.fetchSpecific}, when passed a sequence for
        C{headerNumber}, sends the I{BODY[N.M]} command.  It returns a
        L{Deferred} which fires with a C{dict} mapping message sequence numbers
        to C{list}s of corresponding message data given by the server's
        response.
        """
        d = self.client.fetchSpecific('7', headerNumber=(1, 2, 3))
        self.assertEqual(
            self.transport.value(), b'0001 FETCH 7 BODY[1.2.3]\r\n')
        self.client.lineReceived(b'* 7 FETCH (BODY[1.2.3] "Some body")')
        self.client.lineReceived(b'0001 OK FETCH completed')
        self.assertEqual(
            self.successResultOf(d),
            {7: [['BODY', ['1.2.3'], "Some body"]]})

        L{IMAP4Client.fetchSpecific}, when passed a sequence for
        C{headerNumber}, sends the I{BODY[N.M]} command.  It returns a
        L{Deferred} which fires with a C{dict} mapping message sequence numbers
        to C{list}s of corresponding message data given by the server's
        response.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/test/test_imap.py