Combinatorics

Combinations with itertools

from itertools import combinations
for _ in combinations('ABCD', 2):
    print(_)

('A', 'B')
('A', 'C')
('A', 'D')
('B', 'C')
('B', 'D')
('C', 'D')

for _ in combinations(range(4), 3):
    print(_)

(0, 1, 2)
(0, 1, 3)
(0, 2, 3)
(1, 2, 3)