我试图在python中建立一个简单的乌龟程序，我可以通过按空格键开始移动乌龟，并且他一直移动直到再次按下空格键。 我可以让他用太空压力机移动固定距离，但无法继续。

这是我正在使用的：

from turtle import *

# PUT YOUR CODE HERE

setup(800,600)

home()

pen_size = 2

color("blue")

title("Turtle")

speed("fastest")

drawdist= 25

current_state = penup

next_state = pendown

#Button Instructions

def move_up():

seth(90)

forward(drawdist)

def move_down():

seth(270)

forward(drawdist)

def move_left():

seth(180)

forward(drawdist)

def move_right():

seth(0)

forward(drawdist)

def space_bar():

seth(90)

forward(drawdist)

global current_state, next_state

next_state()

current_state, next_state = next_state, current_state

#Change Pen Color

def red():

color("red")

def green():

color("green")

def blue():

color("blue")

#Button Triggers

s= getscreen()

s.onkey(move_up,"Up")

s.onkey(move_down,"Down")

s.onkey(move_left,"Left")

s.onkey(move_right,"Right")

s.onkey(space_bar,"space")

s.onkey(red,"r")

s.onkey(green,"g")

s.onkey(blue,"b")

listen()

done()