def test_fetchSpecificNumberedText(self):
        """
        If passed a value for the C{headerNumber} parameter and C{'TEXT'} for
        the C{headerType} parameter, L{IMAP4Client.fetchSpecific} sends a
        I{BODY[number.TEXT]} request and returns a L{Deferred} which fires with
        a C{dict} mapping message sequence numbers to C{list}s of message data
        given by the server's response.
        """
        d = self.client.fetchSpecific('4', headerType='TEXT', headerNumber=7)
        self.assertEqual(
            self.transport.value(), b'0001 FETCH 4 BODY[7.TEXT]\r\n')
        self.client.lineReceived(b'* 4 FETCH (BODY[7.TEXT] "Some body")')
        self.client.lineReceived(b'0001 OK FETCH completed')
        self.assertEqual(
            self.successResultOf(d),
            {4: [['BODY', ['7.TEXT'], "Some body"]]})

        If passed a value for the C{headerNumber} parameter and C{'TEXT'} for
        the C{headerType} parameter, L{IMAP4Client.fetchSpecific} sends a
        I{BODY[number.TEXT]} request and returns a L{Deferred} which fires with
        a C{dict} mapping message sequence numbers to C{list}s of message data
        given by the server's response.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/test/test_imap.py