'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;
  };