code: def get_node(self, node_id):
          
  
          try:
              UUID(node_id, version=4)
          except ValueError:
              raise aiohttp.web.HTTPBadRequest(text="Node ID {} is not a valid UUID".format(node_id))
  
          for node in self._nodes:
              if node.id == node_id:
                  return node
  
          raise aiohttp.web.HTTPNotFound(text="Node ID {} doesn't exist".format(node_id))
docs: Returns a Node instance.
  
          :param node_id: Node identifier
  
          :returns: Node instance