eight queens solution from Beginning Python

eight_queens.py

import random


def conflict(state, nextX):
    nextY = len(state)
    for i in range(nextY):
        if abs(state[i] - nextX) in (0, nextY - i):
            return True
    return False


def queens(num=8, state=()):
    for pos in range(num):
        if not conflict(state, pos):
            if len(state) == num - 1:
                yield (pos, )
            else:
                for result in queens(num, state + (pos, )):
                    yield (pos, ) + result


def prettyprint(solution):
    def line(pos, length=len(solution)):
        return '. ' * (pos) + 'X' + ' .' * (length - pos - 1)
    for pos in solution:
        print line(pos)


result = list(queens())
prettyprint(random.choice(result))
#print result
print len(result)