shell bypass 403
'use strict';
var validTypes = { object: true, symbol: true };
module.exports = function () {
var symbol;
if (typeof Symbol !== 'function') return false;
symbol = Symbol('test symbol');
try { String(symbol); } catch (e) { return false; }
// Return 'true' also for polyfills
if (!validTypes[typeof Symbol.iterator]) return false;
if (!validTypes[typeof Symbol.toPrimitive]) return false;
if (!validTypes[typeof Symbol.toStringTag]) return false;
return true;
};