static boolean legalOperatorP(Symbol operator) {
    return (Logic.$KIF_SENTENCE_OPERATORS$.memberP(operator) ||
        (Logic.$KIF_TERM_OPERATORS$.memberP(operator) ||
         Stella.getQuotedTree("((<=>> <<=> <<=>> <~> <~>> <<~> <<~>> ABOUT <<= =>> <~ ~> <<~ ~>>) \"/PLI\")", "/PLI").memberP(operator)));
  }