'use strict'; var toString = Object.prototype.toString , toStringTagSymbol = require('es6-symbol').toStringTag , id = '[object Set]' , Global = (typeof Set === 'undefined') ? null : Set; module.exports = function (x) { return (x && ((Global && ((x instanceof Global) || (x === Global.prototype))) || (toString.call(x) === id) || (x[toStringTagSymbol] === 'Set'))) || false; };