docs: def action_fluent_variables(self) -> FluentParamsList:
          '''Returns the instantiated action fluents in canonical order.
  
          Returns:
              Sequence[Tuple[str, List[str]]]: A tuple of pairs of fluent name
              and a list of instantiated fluents represented as strings.
          '''
          fluents = self.domain.action_fluents
          ordering = self.domain.action_fluent_ordering
          return self._fluent_params(fluents, ordering)