whole_func_string: function append(parent, child) {
              if (parent.el !== undefined && child.el !== undefined) {
                  parent.el.appendChild(child.el);
              }
          }
func_code_string: function append(parent, child) {
              if (parent.el !== undefined && child.el !== undefined) {
                  parent.el.appendChild(child.el);
              }
          }
func_documentation_string: Insert element to the end of parent childs  @method append @param {dom.Element} parent @param {dom.Element} child