def collide(a, b):
    left_a, bottom_a, right_a, top_a = a.get_bb()
    left_b, bottom_b, right_b, top_b = b.get_bb()

    #if left_a > right_b : return False
    #if right_a < left_b : return False
    #if top_a < bottom_b : return False
    #if bottom_a > top_b : return False


    if right_a < left_b or left_a > right_b:
        return False
    elif top_a < bottom_b or bottom_a > top_b:
        return False

   #print "Collide! %s %s" % (a, b)

    return True