Много мячиков, прыгающий по воздествием притяжения

Ниже представлен код из видео

import turtle, random
border = turtle.Turtle()
border.hideturtle()
border.speed(0)
border.pensize(5)
border.up()
border.goto(-250,250)
border.down()
border.goto(-250,-250)
border.goto(250,-250)
border.goto(250,250)

window = turtle.Screen()
window.bgcolor('yellow')

balls = []
count = 5
forms = ['circle', 'square', 'triangle', 'turtle']

for i in range(count):
    ball = turtle.Turtle(shape=random.choice(forms))
    red = random.random()
    green = random.random()
    blue = random.random()
    ball.color(red, green, blue)
    ball.up()
    ball.goto(random.randint(-200,200),random.randint(100,300))
    ball.speedY = 0
    ball.speedX = random.randint(-3,3)
    balls.append(ball)

gravitation = 0.1

while True:
    for ball in balls:
        ball.speedY = ball.speedY - gravitation
        ball.goto(ball.xcor()+ball.speedX, ball.ycor()+ball.speedY)

        if ball.ycor() <= -250:
            ball.speedY = -ball.speedY

        if ball.xcor() >= 250 or ball.xcor() <= -250:
            ball.speedX = -ball.speedX

window.mainloop()