当我告诉我的Python程序运行时，它就在那里

Question

我的节目是：

def start():
choice = 0
print("You see a dark cave ahead, and a castle in the distance")
while choice == 0:
  print("OPTIONS: CAVE; CASTLE")
  x = str(input())
  if x.lower() == "cave":
    cave()
    choice = 1
  elif x.lower() == "castle":
    castle()
    choice = 1
  else:
    print("That is not an option. Please try again")

当我跑它时，它只是坐在那里并没有做任何事情。我发现它没有任何问题。有什么提示吗？