code: function(shape, index) {
                  var parent = this.getShapeNode();
                  parent.insertBefore(shape.node, parent.childNodes[index] || null);
                  shape.trigger("add", {
                      container: this
                  });
                  if (shape.notifyTreeModification) {
                      shape.notifyTreeModification("treeadd", this);
                  }
              }
docs: /* private