# permutations.py

import itertools

for p in itertools.permutations([1, 2, 3, 4], 3):
    print(''.join(['abcd'[i-1] for i in p]))
'''
abc
abd
acb
acd
adb
adc
bac
bad
bca
bcd
bda
bdc
cab
cad
cba
cbd
cda
cdb
dab
dac
dba
dbc
dca
dcb
'''