code: def rank_path(graph, path, edge_ranking=None):
      
      edge_ranking = default_edge_ranking if edge_ranking is None else edge_ranking
  
      return sum(max(edge_ranking[d[RELATION]] for d in graph.edge[u][v].values()) for u, v in pairwise(path))
docs: Takes in a path (a list of nodes in the graph) and calculates a score
  
      :param pybel.BELGraph graph: A BEL graph
      :param list[tuple] path: A list of nodes in the path (includes terminal nodes)
      :param dict edge_ranking: A dictionary of {relationship: score}
      :return: The score for the edge
      :rtype: int