How to bounce a ball within a square?

[andreachilam]

I am doing a project of creating a playing pool and 2 balls bouncing within the pool. I have tried to use "while loop" and "if statement" to set restriction limiting the ball not to bounce out of the pool. However, the ball doesn't move or bounce.

It moves but stops after it hits one of the walls when I write this function below:

def move_ball(heading):
    t1=turtle.Pen()
    t1.color("yellow")
    t1.shape("circle")
    x,y=turtle.position()
    while 200 > (t1.xcor()) >-200 and -90< (t1.ycor())<90:
        t1.forward(1)
        t1.setheading(heading)  

But, it doesn't move at all when I write this function below:

# here I try to do all restrictions of 4 walls  
 
# just 2 walls here
 
def wall_bottom(heading):
    t1=turtle.Pen()
    t1.color("yellow")
    t1.shape("circle")
    current=0
    if 100<t1.ycor()<-100:
        if 270 < t1.setheading() < 360:
            t1.forward(1)
            t1.setheading(0+(360-(t1.heading())))
        else:
            t1.forward(1)
            t1.setheading(180-(t1.heading()-180))
 
def wall_top(heading):
    t1=turtle.Pen()
    t1.color("yellow")
    t1.shape("circle")
    if 200> t1.xcor() >-200:
        if 90> t1.setheading()<0:
            t1.forward(1)
            t1.setheading(0-(180-(t1.heading())))
        else:
            t1.forward(1)
            t1.setheading(180-(t1.heading()-180))

I don't know if I am doing the right things. This is so confusing. Please Help me for this. I want the ball bounce. Thanks!