Get a specific part from the message and print it raw.

def getrawpartid(self, msgid, partid, stream=sys.stdout):
        """Get a specific part from the message and print it raw.
        """
        parts = [part for hdr,part in self._get(msgid)]
        part = parts[int(partid)]
        pl = part.get_payload(decode=True)
        if pl != None:
            print(pl, file=stream)