Retrieves descriptor options.

    This method returns the options set or creates the default options for the
    descriptor.

def GetOptions(self):
    """Retrieves descriptor options.

    This method returns the options set or creates the default options for the
    descriptor.
    """
    if self._options:
      return self._options
    from google.protobuf import descriptor_pb2
    try:
      options_class = getattr(descriptor_pb2, self._options_class_name)
    except AttributeError:
      raise RuntimeError('Unknown options class name %s!' %
                         (self._options_class_name))
    self._options = options_class()
    return self._options