code: function(index) {
      if(lang.isNumber(index) && this._elColgroup && this._elColgroup.childNodes[index]) {
          this._elColgroup.removeChild(this._elColgroup.childNodes[index]);
      }
  }
docs: Removes a COL element to COLGROUP at given index.
  
  @method _removeColgroupColEl
  @param index {Number} Index of removed COL element.
  @private