perms.py

import math

def permutations(to_go, path_taken='', paths=[]):
    if not to_go:
        print(path_taken)
        paths.append(path_taken)
    else:
        for i in range(len(to_go)):
            here = to_go[i]
            elsewhere = to_go[:i] + to_go[i+1:]
            permutations(elsewhere, path_taken + here)
    return paths


s = "abcd"
p = permutations(s)
assert len(p) == math.factorial(len(s)), f"There should be {len(s)}! permutations"
print(f"Found {len(p)} permutations of '{s}'")