0* put weight in basket, throw it down (weight is on the ground now)
1: bring-the-kids-down (at the end the weight is in the tower)
2: 165 joins 90 into basket, 195 joins 75 into basket
3* bring 195 + 75 down while the 165 + 90 go up (pulley runs) 
4: tell kids to go in tower, then queen must jump out (weight stays at ground level) 
5: bring-the-kids-down (the weight ends up in tower)


def bring-the-kids-down():
  # preconditions: both kids are in the tower and the weight on the ground
  1. bring-prince-down
  2. prince jumps out of the basket, weight falls to the ground
  3. bring-princess-down
  4. bring-prince-down
  # postconditions: at the end prince is in basket, weight at tower height 

def bring-prince-down:
  # basket1: prince, tower; basket2: weight, ground
  prince -> ground, weight -> tower


def bring-princess-down:
  # 165 in basket, tower; 90 + 75 in basket on ground
  165 -> ground, 90 + 75 -> tower
  prince jumps, princess jumps, weight falls
  # prince in tower, weight, princess down