3 var toString = Object.prototype.toString
4 , toStringTagSymbol = require('es6-symbol').toStringTag
7 , Global = (typeof Set === 'undefined') ? null : Set;
9 module.exports = function (x) {
10 return (x && ((Global && (x instanceof Global)) ||
11 (toString.call(x) === id) || (x[toStringTagSymbol] === 'Set'))) || false;