code: def attribute_nodes(self):
          
          impl_attr_nodes = self.adapter.get_node_attributes(self.impl_node)
          wrapped_attr_nodes = [
              self.adapter.wrap_node(a, self.adapter.impl_document, self.adapter)
              for a in impl_attr_nodes]
          return sorted(wrapped_attr_nodes, key=lambda x: x.name)
docs: :return: a list of this element's attributes as
              :class:`Attribute` nodes.