import turtle
import random
import math
screen = turtle.Screen() 
screen.bgcolor('yellow')
# Set up boundry box size
xMax=200
xMin=-200
yMax=200
yMin=-200
# Function to draw a box to bounce in
def makeBoundary(right,left,top,bottom):
  # Finish Function...
  return
# Function to setup ball
def setupBall(ball,x,y,dX):
  # Set up starting values
  ball.penup()
  ball.shape('circle')
  # x, y, dX are object variables
  ball.x=x
  ball.y=y
  # We should make this random
  ball.dX=dX
  # Place ball at starting point
  ball.goto(ball.x,ball.y)
# Function to animate ball one step
def animate(ball):
  # use globals for boundries
  global xMax,xMin,yMax,yMin
  # Code here to bounce off the walls
  if ball.x > xMax or ball.x < xMin:
    # Reverse direction
    ball.dX = -ball.dX
  # Move to next position
  ball.x+=ball.dX
  ball.goto(ball.x,ball.y)
  
# Call function to draw box
makeBoundary(xMax,xMin,yMax,yMin)
# create turtle, and initialize it
ball1 = turtle.Turtle()
setupBall(ball1,0,0,2)
# Animate!
while (True):
  animate(ball1);