code: def _default_node_children(self, node, visitor, children):
          
          return {
              self.model._cte_node_children: [
                  self.node_as_tree(child, visitor=visitor, children=children)
                  for child in node.children.all()
              ]
          }
docs: Generates a key and list of children of the given :class:`CTENode`
          `node`, intended to be used as an update to the dictionary
          representation generated by the :meth:`node_as_tree` method. The key is
          ``children`` and the list consists of the children of the given node as
          determined by the `children` callback.
  
          Each child node is, in turn, visited through recursive calls to
          :meth:`node_as_child`, and the `visitor` and `children` parameters are
          passed along.
  
          :param node: the :class:`CTENode` for which to generate the children
              representation.
  
          :param visitor: optional function responsible for generating the
              dictionary representation of the node.
  
          :param children: optional function responsible for generating a
              children key and list for the node.
  
          :return: a key and list representation of the structure of the children
              of the given node.