* @return boolean
   */
  public static boolean functionP(Stella_Object relationref) {
    { Stella_Object instance = Logic.getInstance(relationref);

      if ((instance == null) ||
          (Logic.SGT_PL_KERNEL_KB_FUNCTION.surrogateValue == null)) {
        return (false);
      }
      else {
        return (Logic.testIsaP(instance, Logic.SGT_PL_KERNEL_KB_FUNCTION));
      }
    }
  }