code: function() {
          var resizeHandleHeights;
  
          this._destroyChildren();
  
          this.$el.css({
              height: this.dimensionModel.get('headerHeight') - TABLE_BORDER_WIDTH
          }).html(this.template({
              colGroup: this._getColGroupMarkup(),
              tBody: this._getTableBodyMarkup()
          }));
  
          if (this.coordColumnModel.get('resizable')) {
              resizeHandleHeights = this._getResizeHandleHeights();
              this._addChildren(this.viewFactory.createHeaderResizeHandle(this.whichSide, resizeHandleHeights));
              this.$el.append(this._renderChildren());
          }
  
          return this;
      }
docs: 랜더링
  @returns {View.Layout.Header} this