pong

import turtle

wn = turtle.Screen()
wn.title("Pong")
wn.bgcolor("blue")
wn.setup(width=800, height=600)
wn.tracer(0)

paddle_a = turtle.Turtle()
paddle_a.speed(0)
paddle_a.shape("square")
paddle_a.color("black")
paddle_a.shapesize(stretch_wid=5, stretch_len=1)
paddle_a.penup()
paddle_a.goto(-350, 0)

paddle_b = turtle.Turtle()
paddle_b.speed(0)
paddle_b.shape("square")
paddle_b.color("black")
paddle_b.shapesize(stretch_wid=5, stretch_len=1)
paddle_b.penup()
paddle_b.goto(350, 0)

ball = turtle.Turtle()
ball.speed(0)
ball.shape("square")
ball.color("black")
ball.penup()
ball.goto(0, 0)

def paddle_a_up():
        y = paddle_a.ycor()
        y += 20
        paddle_a.sety(y)

        wn.listen()
        wn.onkeypress(paddle_a_up, "w")





while True:
    wn.update()