code: def _call_ver2(self, file_path, mode='r', buffering=-1, flags=None,
                     open_modes=None):
          
          # Backwards compatibility, mode arg used to be named flags
          mode = flags or mode
          return self.call(file_path, mode, buffering, open_modes=open_modes)
docs: Limits args of open() or file() for Python 2.x versions.