docs: def _take_extras(self, item: Parameter) -> Optional[bool]:
          """Return either this GPflow objects requires compilation at decoding time.
  
          :param item: GPflow parameter.
          :return: None or True value.
          """
  
          index = item.tf_compilation_index()
          if index is not None:
              if item.index == index:
                  return True
              _add_index_to_compilations(self.context, index)
          return None