今日のpython error: invalid keyword argument for this function

組み合わせ爆発の凄さ
https://qiita.com/kaizen_nagoya/items/f309b0c2bb015bbc71c3

で、

graphillionを使ってみた
https://qiita.com/cabernet_rock/items/50f955afc16287244154

をファイルにした。

実行しても何も出ない。

printを加えた。

gra.py

# https://qiita.com/cabernet_rock/items/50f955afc16287244154
# 必要なモジュールのインポート
from graphillion import GraphSet
import graphillion.tutorial as tl
import time              # 計算時間を調べる。
# グリッドのサイズを指定
universe = tl.grid(2, 2)
GraphSet.set_universe(universe)
tl.draw(universe)
start = 1 # スタート位置
goal = 9 # ゴールの位置
paths = GraphSet.paths(start, goal)
print (len(paths))
#
key = 4        # 1箇所目
treasure = 2   # 2箇所目
paths_to_key = GraphSet.paths(start, key).excluding(treasure)
treasure_paths = paths.including(paths_to_key).including(treasure)
print (len(treasure_paths))
#
universe = tl.grid(8, 8) # 9×9のグリッド
GraphSet.set_universe(universe)
start = 1
goal = 81
s = time.time()          # 計算開始時刻
print  (paths = GraphSet.paths(start, goal))
time.time() - s # 計算時間
print (len(paths))

docker/ubuntu

# python3 gra.py
12
2
Traceback (most recent call last):
  File "gra.py", line 26, in <module>
    print  (paths = GraphSet.paths(start, goal))
TypeError: 'paths' is an invalid keyword argument for this function

print (paths = GraphSet.paths(start, goal))

を

paths = GraphSet.paths(start, goal)
print (paths)

に変更。