Pong .py

import turtle
wn=turtle.Screen()
wn.title("Pong by @Dheeraj")
wn.bgcolor("black")
wn.setup(width=800, height=600)
wn.tracer(0)
#padle A
paddle_a=turtle.Turtle()
paddle_a.speed(0)
paddle_a.shape("square")
paddle_a.color("Blue")
paddle_a.shapesize(stretch_wid=5,stretch_len=1)
paddle_a.penup()
paddle_a.goto(-350,0)
#paddle B
paddle_b=turtle.Turtle()
paddle_b.speed(0)
paddle_b.shape("square")
paddle_b.color("red")
paddle_b.shapesize(stretch_wid=5,stretch_len=1)
paddle_b.penup()
paddle_b.goto(350,0)
#ball
ball =turtle.Turtle()
ball.speed(0)
ball.shape("square")
ball.color("white")
ball.penup()
ball.goto(0,0)
ball.dx=-0.3
ball.dy=-0.3 # ball move by two pixels

#function
def paddle_a_up():
    y = paddle_a.ycor()
    y+=20
    paddle_a.sety(y)
def paddle_a_down():
    y = paddle_a.ycor()
    y-=20
    paddle_a.sety(y)
def paddle_b_up():
    y = paddle_b.ycor()
    y+=20
    paddle_b.sety(y)
def paddle_b_down():
    y = paddle_b.ycor()
    y-=20
    paddle_b.sety(y)
#key word binding
wn.listen()
wn.onkeypress(paddle_a_up, "w")
wn.onkeypress(paddle_a_down, "s")
wn.onkeypress(paddle_b_up, "Up")
wn.onkeypress(paddle_b_down, "Down")



###main game loop
while True:
   wn.update()
   #move the ball
   ball.setx(ball.xcor()+ball.dx)
   ball.sety(ball.ycor()+ball.dy)
    #border checking
   if ball.ycor()>290:
       ball.sety(290)
       ball.dy*=-1
   if ball.ycor()<-290:
       ball.sety(-290)
       ball.dy*=-1
   if ball.xcor()<-390:
       ball.goto(0,0)
       ball.dx*=-1
   if ball.xcor()>390:
       ball.goto(0,0)
       ball.dx*=-1
       #paddle and ball collisions

   if  ball.xcor()>340 and ball.xcor()<350 and (ball.ycor()<paddle_b.ycor()+40 and ball.ycor()>paddle_b.ycor()-40):
       ball.setx(340)

       ball.dx*=-1
   if  ball.xcor()<-340 and ball.xcor()>-350 and (ball.ycor()<paddle_a.ycor()+40 and ball.ycor()>paddle_a.ycor()-40):
       ball.setx(-340)

       ball.dx*=-1