>>> from itertools import combinations
>>> list(combinations([1,2,3,5,7],2))
[(1, 2), (1, 3), (1, 5), (1, 7), (2, 3), (2, 5), (2, 7), (3, 5), (3, 7), (5, 7)]
>>> list(combinations([1,2,3,5,7],3))
[(1, 2, 3), (1, 2, 5), (1, 2, 7), (1, 3, 5), (1, 3, 7), (1, 5, 7), (2, 3, 5), (2, 3, 7), (2, 5, 7), (3, 5, 7)]