function evaluate(script, clients) {
        return _send(
            {
                method: "Runtime.evaluate",
                params: {
                    expression: script
                }
            },
            clients
        );
    }
Protocol method. Evaluates the given script in the browser (in global context), and returns a promise
that will be fulfilled with the result of the script, if any.
@param {number|Array.<number>} clients A client ID or array of client IDs that should evaluate
     the script.
@param {string} script The script to evaluate.
@return {$.Promise} A promise that's resolved with the return value from the first client that responds
     to the evaluation.