docs: function() {
          var i = 0,
              arg = arguments,
              l = arguments.length,
              obj;
          for (; i < l; ++i) {
              obj = arg[i];
              if (obj._parent) {
                  obj._parent.detach(obj);
              }
              obj._parent = this;
              this._children.push(obj);
          }
  
          return this;
      }