Generator for cartesian product

cartesian.py

def cartesian(lol):
    if not lol:
        yield []
    else:
        left, right = lol[0], lol[1:]
        for item in left:
            for result in cartesian(right):
                yield [item] + result

>>> data = [
...     [1, 2, 3],
...     [4, 5],
...     [6, 7, 8],
... ]
>>> print(list(cartesian(data)))
[[1, 4, 6], [1, 4, 7], [1, 4, 8], [1, 5, 6], [1, 5, 7], [1, 5, 8], [2, 4, 6], [2, 4, 7], [2, 4, 8], [2, 5, 6], [2, 5, 7], [2, 5, 8], [3, 4, 6], [3, 4, 7], [3, 4, 8], [3, 5, 6], [3, 5, 7], [3, 5, 8]]