code: def get_node(self, index: int) -> Optional[Node]:
          
          return self._nodes.get(index)
docs: Returns the node with the given index if such a node currently exists in the node list.
  
          Arguments:
              index (int): The index of the queried node.
  
          Returns:
              The node with the given index if such a node currently exists in the node list,
              `None` otherwise.