Python All Combinations

all-combinations.py

from functools import reduce

list3 = [
    ['S1', 'S2'],
    ['O1', 'O2'],
    ['F1'],
    ['A1', 'A2']
]

result = list3[0]

def merge(x, y):
    if not isinstance(x, list) and not isinstance(y, list):
        return [x,y]
    elif isinstance(x, list) and isinstance(y, list):
        return x + y
    elif isinstance(x, list) and not isinstance(y, list):
        x.append(y)
        return x
    elif not isinstance(x, list) and isinstance(y, list):
        y.append(x)
        return y

for index in range(1, len(list3)):
    next = list3[index]
    result = list(map(lambda x: list(map(lambda y: merge(x,y),  result)), next))
    result = reduce(lambda x, y: x + y, result)

for x in result:
    print(x)