Generates attributes values of specific nodes

def nx_gen_node_values(G, key, nodes, default=util_const.NoParam):
    """
    Generates attributes values of specific nodes
    """
    node_dict = nx_node_dict(G)
    if default is util_const.NoParam:
        return (node_dict[n][key] for n in nodes)
    else:
        return (node_dict[n].get(key, default) for n in nodes)