def __setitem__(self, key, message):
        """Replace the keyed message; raise KeyError if it doesn't exist."""
        path = os.path.join(self._path, str(key))
        try:
            f = open(path, 'rb+')
        except IOError, e:
            if e.errno == errno.ENOENT:
                raise KeyError('No message with key: %s' + key)
            else:
                raise
        try:
            if self._locked:
                _lock_file(f)
            try:
                os.close(os.open(path, os.O_WRONLY | os.O_TRUNC))
                self._dump_message(message, f)
                if isinstance(message, MHMessage):
                    self._dump_sequences(message, key)
            finally:
                if self._locked:
                    _unlock_file(f)
        finally:
            _sync_close(f)
dataset/ETHPy150Open babble/babble/include/jython/Lib/mailbox.py/MH.__setitem__/operator `%` -> `+`