text: var isES5 = (function(){
      "use strict";
      return this === undefined;
  })();
  
  if (isES5) {
      module.exports = {
          freeze: Object.freeze,
          defineProperty: Object.defineProperty,
          keys: Object.keys,
          getPrototypeOf: Object.getPrototypeOf,
          isArray: Array.isArray,
          isES5: isES5,
          propertyIsWritable: function(obj, prop) {
              var descriptor = Object.getOwnPropertyDescriptor(obj, prop);
              return !!(!descriptor || descriptor.writable || descriptor.set);
          }
      };
  } else {
      var has = {}.hasOwnProperty;
      var str = {}.toString;
      var proto = {}.constructor.prototype;
  
      var ObjectKeys = function (o) {
          var ret = [];
          for (var key in o) {
              if (has.call(o, key)) {
                  ret.push(key);
              }
          }
          return ret;
      };
  
      var ObjectDefineProperty = function (o, key, desc) {
          o[key] = desc.value;
          return o;
      };
  
      var ObjectFreeze = function (obj) {
          return obj;
      };
  
      var ObjectGetPrototypeOf = function (obj) {
          try {
              return Object(obj).constructor.prototype;
          }
          catch (e) {
              return proto;
          }
      };
  
      var ArrayIsArray = function (obj) {
          try {
              return str.call(obj) === "[object Array]";
          }
          catch(e) {
              return false;
          }
      };
  
      module.exports = {
          isArray: ArrayIsArray,
          keys: ObjectKeys,
          defineProperty: ObjectDefineProperty,
          freeze: ObjectFreeze,
          getPrototypeOf: ObjectGetPrototypeOf,
          isES5: isES5,
          propertyIsWritable: function() {
              return true;
          }
      };
  }
  