title: My Python turtle doesn't work when ran in python shell
body: <p>I am using the Python turtle module and have created the code below: </p>
  
  <pre><code>import turtle
  
  def draw_square(some_turtle) :
      some_turtle.forward(100)
      some_turtle.right(90)
      some_turtle.forward(6)
      some_turtle.right(90)
      some_turtle.forward(100)
      some_turtle.left(90)
      some_turtle.forward(6)
      some_turtle.left(90)
  
  def draw_art():
      window = turtle.Screen()
      window.bgcolor("green")
      brad = turtle.Turtle()
      brad.shape("turtle")
      brad.color("red")
      brad.speed(50)
      for i in range(1,10) :
          draw_square(brad)
      window.exitonclick()
  
  draw_art()
  </code></pre>
  
  <p>I want this code to draw a square, but it doesn't. 
  Can you explain why this doesn't work? 
  problem: I see shell stops working.... ;; can't do more job I want to ... 
            when I click, It doesn't move at all </p>