637         try:

   637         try:

   638             return self._data[k]

   638             return self._data[k]

   639         except KeyError:

   639         except KeyError:

   640             return default

   640             return default

   641 

   641 

   642     def __getitem__(self, k):

   647     def __getitem__(self, k):

   643         with self._lock:

   648         with self._lock:

   644             if k in self._permanent:

   649             if k in self._permanent:

   645                 return self._data[k]

   650                 return self._data[k]

   646             v = self._transient.get(k, _MARKER)

   651             v = self._transient.get(k, _MARKER)