docs: def route_has_dead_links(root, machine):
      """Quickly determine if a route uses any dead links.
  
      Parameters
      ----------
      root : :py:class:`~rig.place_and_route.routing_tree.RoutingTree`
          The root of the RoutingTree which contains nothing but RoutingTrees
          (i.e. no vertices and links).
      machine : :py:class:`~rig.place_and_route.Machine`
          The machine in which the routes exist.
  
      Returns
      -------
      bool
          True if the route uses any dead/missing links, False otherwise.
      """
      for direction, (x, y), routes in root.traverse():
          for route in routes:
              if (x, y, route) not in machine:
                  return True
      return False