itertools

import itertools

• accumulate( iterable, [ func, *, initial=None ] ): 누적합
• permutations( iterable, r=None ): 순열
• product( *iterables, repeat=1 ), 곱집합 or 카타시안 곱
• combinations( iterable, r ), 조합
• combinations_with_replacement( iterable, r ), 중복 조합