code: function () {
        var len = _emberMetalProperty_get.get(this, 'length');
        if (len === 0) {
          return null;
        }
  
        var ret = _emberRuntimeMixinsArray.objectAt(this, len - 1);
        this.removeAt(len - 1, 1);
        return ret;
      }
docs: Pop object from array or nil if none are left. Works just like `pop()` but
  it is KVO-compliant.
  ```javascript
  var colors = ['red', 'green', 'blue'];
  colors.popObject();   // 'blue'
  console.log(colors);  // ['red', 'green']
  ```
  @method popObject
  @return object
  @public