title: Python turtle.Terminator error
body: <p>When i am using turtle module to draw a circle with this simple function:</p>
  
  <pre><code>def draw_shape(self):
      canvas = Screen()
      t = Turtle()
      t.circle(self.r)
      canvas.exitonclick()
  </code></pre>
  
  <p>For the first time when i call this function it opens a new window and draw a circle, i click on it to exit and when i try to again call this function from menu in console i got an error:</p>
  
  <pre><code>Original exception was:
  Traceback (most recent call last):
    File "main.py", line 136, in &lt;module&gt;
      main()
    File "main.py", line 132, in main
      OPTIONS[user_input][1](shapes)
    File "main.py", line 48, in handle_sixth_menu_option
      t = Turtle()
    File "/usr/lib/python3.6/turtle.py", line 3816, in __init__
      visible=visible)
    File "/usr/lib/python3.6/turtle.py", line 2557, in __init__
      self._update()
    File "/usr/lib/python3.6/turtle.py", line 2660, in _update
      self._update_data()
    File "/usr/lib/python3.6/turtle.py", line 2646, in _update_data
      self.screen._incrementudc()
    File "/usr/lib/python3.6/turtle.py", line 1292, in _incrementudc
      raise Terminator
  turtle.Terminator
  </code></pre>