def find_pseudo_peripheral_node_pair(G, start=None):
    # helper for cuthill-mckee to find a "pseudo peripheral pair"
    # to use as good starting node 
    if start != None:
        u = next(G.nodes_iter())
    else:
        u = start
    lp = 0
    v = u 
    while True:
        spl = nx.shortest_path_length(G, v)
        l = max(spl.values())
        if l <= lp: 
            break
        lp = l
        farthest = [n for n,dist in spl.items() if dist==l]
        v, deg = sorted(G.degree(farthest).items(), key=itemgetter(1))[0]
    return u, v
dataset/ETHPy150Open gkno/gkno_launcher/src/networkx/utils/rcm.py/find_pseudo_peripheral_node_pair/operator `is` -> `!=`