Conway's game of life

conway.py

def tick(world):
    output_world = world.copy()

    if len(world) <= 2:
        return set()

    for cell in world:
        if len(get_live_neighbors(cell, world)) < 2:
            output_world.remove(cell)

        neighbors = get_neighbors(cell)
        dead_neighbors = neighbors.difference(world)

        for n in dead_neighbors:
            if len(get_live_neighbors(n,world)) == 3:
                output_world.add(n)

    return output_world

def get_neighbors(cell):
    world = set(([(x,y) for x in range(cell[0]-1, cell[0] + 2)
        for y in range(cell[1] - 1, cell[1] + 2)]))
    world.remove(cell)
    return world

def get_live_neighbors(cell, world):
    neighbors = get_neighbors(cell)
    return world.intersection(neighbors)