is-implemented.js 317 Bytes
"use strict";

var global   = require("ext/global-this")
  , polyfill = require("../polyfill");

module.exports = function (t, a) {
	var cache;
	a(typeof t(), "boolean");
	cache = global.Symbol;
	global.Symbol = polyfill;
	a(t(), true);
	if (cache === undefined) delete global.Symbol;
	else global.Symbol = cache;
};