alternative to http://users.softlab.ntua.gr/~ttsiod/yield.html

permute.py

def permute(queue, final = []):
    for item in queue:
        remaining_queue, pending = [e for e in queue if e is not item], final + [item]
        if remaining_queue:
            for more in permute(remaining_queue, pending):
                yield more
        else:
            yield pending