* @param module
   * @param environment
   * @return PlIterator
   */
  public static PlIterator sGetRelationExtension(String relationName, Module module, Environment environment) {
    { Stella_Object relation = PLI.safelyGetRelation(relationName, module, environment);

      if (relation != null) {
        return (PLI.getRelationExtension(((LogicObject)(relation)), module, environment));
      }
      else {
        return (PLI.EMPTY_PL_ITERATOR);
      }
    }
  }