def next(self):
        while 1:
            self.fp.seek(self.seekp)
            try:
                self._search_start()
            except EOFError:
                self.seekp = self.fp.tell()
                return None
            start = self.fp.tell()
            self._search_end()
            self.seekp = stop = self.fp.tell()
            if start != stop:
                break
        return self.factory(_PartialFile(self.fp, start, stop))

# Recommended to use PortableUnixMailbox instead!
dataset/ETHPy150Open babble/babble/include/jython/Lib/mailbox.py/_Mailbox.next/original