Shooting ball hELP?

[jib]

the point of the game is to shoot the bouncing ball. However i am trying to make the shooter move from left ot right any help is appreciated

from turtle import *
from random import *
import winsound
import math

def shooter_clicked(clickx,clicky): 
    global start
    start=True
    return
    
setup(600,400)

maxx = 300
maxy = 200
minx= -maxx
miny= - maxy

title ("shooting ball")
bgcolor('grey')
ball=Turtle()

ball.penup()
ball.shape("circle")
ball.shapesize(3,3,3)
ball.color("blue")
ball.speed()
bounce_point = 20

shooter=Turtle()
shooter.hideturtle()
shooter.penup()
shooter.shape("square")
shooter.shapesize(3,3,3)
shooter.color("red")
shooter.goto(-10,-140)


bullet=Turtle()
bullet.hideturtle()
bullet.penup()
bullet.shape("circle")
bullet.shapesize(1,1,1)
bullet.goto(-20,-100)

shooter.onclick(shooter_clicked)

x = randint(minx + bounce_point, maxx + bounce_point)
y = randint(miny + bounce_point, maxy + bounce_point)
ball.goto(x,y)

ball.showturtle()
bullet.showturtle()
shooter.showturtle()

dx = 5
dy = 5
bdy=30
by=-140
endloop = False
start=False

while not endloop:


    xx = x + dx


    if xx < minx-bounce_point:
        xx = minx + bounce_point
        dx = -dx
        

    if xx > maxx - bounce_point:
        xx = maxx- bounce_point
        dx = -dx
        


    yy=y+dy
    if yy < miny - bounce_point: 
        yy= miny + bounce_point
        dy = -dy
        

    if yy > maxy+ bounce_point:   
        yy = maxy + bounce_point
        dy = -dy
        


    x = xx
    y = yy
    ball.goto(x,y)
    if start==True:
        by=by+bdy
        if by>maxy:
            by=-170
            start=False
            

        if bullet.distance(ball)<40:
            print"target affirmed"
            print"You win!!!!!!"
            endloop=True
            start=False
            print" game over"
        bullet.goto(0,by)
           
bye()