how to calculate possible permutations python code example

Example 1: all permutations python

import itertools
print(list(itertools.permutations([1,2,3])))

Example 2: python all permutations of a string

>>> from itertools import permutations
>>> perms = [''.join(p) for p in permutations('stack')]
>>> perms

Example 3: python permutation

import itertools

a = [1, 2, 3]
n = 3

perm_iterator = itertools.permutations(a, n)

for item in perm_iterator:
    print(item)