def safe(q1, q2):
    (q1x, q1y) = q1
    (q2x, q2y) = q2
    return q1x != q2x and q1y != q2y and abs(q1x - q2x) != abs(q1y - q2y)

def possible_positions(current, n):
    return ((*current, y) for y in range(n) if all(safe((len(current), y), q) for q in enumerate(current)))

def solutions_r(current, n = 8):
    if len(current) == n:
        yield current
        return

    for pos in possible_positions(current, n):
        yield from solutions_r(pos, n)

def solutions(n = 8):
    return solutions_r((), n)