Answer by cdlane for Indefinitely move Python turtle while allowing input

An event-driven environment like turtle should never have while True: as it potentially blocks out events (e.g. keyboard). Use an ontimer() event instead.

Generally, onkey() and listen() don't belong in a loop -- for most programs they only need to be called once.

Here's a skeletal example of an autonomous turtle being redirected by user input:

from turtle import Screen, Turtledef right():    snake.setheading(0)def up():    snake.setheading(90)def left():    snake.setheading(180)def down():    snake.setheading(270)def movesnake():    snake.forward(1)    screen.ontimer(movesnake, 100)snake = Turtle("turtle")screen = Screen()screen.onkey(right, "Right")screen.onkey(up, "Up")screen.onkey(left, "Left")screen.onkey(down, "Down")screen.listen()movesnake()screen.mainloop()