Python itertools를 이용한 순열과 조합 (combinations, permutations)

import itertools
abc = [1,2,3,4]
#abc = ['a','b','c','d']
b = itertools.permutations(abc, 3) #target, length(Non-Essential)
 
for i in b:
    #i = list(i)
    print(list(i))
    
b = itertools.combinations(abc, 2) #target, length(Essential)
for i in b:
    #i = list(i)
    print(list(i))