parameters: (self, key)
docstring: Return the keyed message; raise KeyError if it doesn't exist.
docstring_summary: Return the keyed message; raise KeyError if it doesn't exist.
docstring_tokens: Return the keyed message ; raise KeyError if it doesn t exist .
function: def __getitem__(self, key):
          """Return the keyed message; raise KeyError if it doesn't exist."""
          if not self._factory:
              return self.get_message(key)
          else:
              return self._factory(self.get_file(key))
function_tokens: def __getitem__ ( self , key ) : if not self . _factory : return self . get_message ( key ) else : return self . _factory ( self . get_file ( key ) )