public Parser valueIsOperand() {
        if (valueIsOperandParser == null) {
           FutureParser future = scoped("valueIsOperand");
           valueIsOperandParser = future;
           future.setParser(
               choice(
                   token("NEXT"),
                   sequence(
                       token("START"),
                       optional(
                           token("OF")
                       ),
                       dataName()
                   ),
                   sequence(
                       token("LENGTH"),
                       optional(
                           token("OF")
                       ),
                       dataName()
                   ),
                   arithmeticExpression(),
                   literal()
               )
           );
        }

        return valueIsOperandParser;
    }