Swap the case of each ASCII letter within a string and print each possible combination to stdout.

swaperoo.py

#!/usr/bin/env python3

import string
import argparse
import itertools
from typing import Iterator


def swaperoo(target: str) -> Iterator[str]:
    '''
    Swap the case of ASCII letters within a string and return
    each possible combination in form of an Iterator.

    Parameters:
        string          input string to perform the swaperoo on

    Returns:
        Iterator[str]   each possible swap combination
    '''
    input_str = list(target)

    filtered = filter(lambda x: x[1] in string.ascii_letters, enumerate(input_str))
    ascii_positions = list(map(lambda x: x[0], filtered))

    for ctr in range(1, len(ascii_positions) + 1):
        for index_set in itertools.combinations(ascii_positions, ctr):

            current = input_str.copy()
            for index in index_set:
                current[index] = current[index].swapcase()

            yield "".join(current)


parser = argparse.ArgumentParser(description='Swap the case of ASCII letters within a string')
parser.add_argument('string', help='string to swap ASCII letters in')
args = parser.parse_args()

for item in swaperoo(args.string):
    print(item)