code: def search_nn_dist(self, point, distance, best=None):
          
  
          results = []
          get_dist = lambda n: n.dist(point)
  
          self._search_nn_dist(point, distance, results, get_dist)
          return results
docs: Search the n nearest nodes of the given point which are within given
          distance
  
          point must be a location, not a node. A list containing the n nearest
          nodes to the point within the distance will be returned.