code: final public Selector ComparisonPredicate() throws ParseException {
                                     Selector left, right; int op;
      left = Expression();
      op = ComparisonOperator();
      right = Expression();
      {if (true) return new OperatorImpl(op, left, right);}
      throw new Error("Missing return statement in function");
    }
docs: | Expression ( "<>" | "=" ) Expression )