RosettaCodeData/Task/Matrix-chain-multiplication/Python/matrix-chain-multiplication-2.py

for u in parens(4):
    print(u)

[0, [1, [2, 3]]]
[0, [[1, 2], 3]]
[[0, 1], [2, 3]]
[[0, [1, 2]], 3]
[[[0, 1], 2], 3]