code: function copy(obj) {
              if (typeof obj !== 'object') return obj;
              if (typeof obj === 'function') return null;
              return JSON.parse(JSON.stringify(obj));
          }
docs: @method copy()
  @for kity.Utils
  @grammar copy(obj) => {object}
  @description 返回一个对象的拷贝副本（深度复制）
  @param  {object} obj 要拷贝的对象
  
  @example
  
  ```js
  var source = {
  key1: {
  key2: 'value2'
  },
  key3: 'value3'
  };
  
  var target = kity.Utils.copy(source);
  
  console.log(target === source); // false
  console.log(target.key1 === source.key1); // false
  console.log(target.key3 === source.key3); // true，因为是值类型
  ```