title: Turtle Subclass "object has no attribute '_shown'"
body: <p>New to Python here.
  I am messing around with Turtle module, and when I try to create a Turtle type class the following way I get the error message:</p>
  <pre><code>AttributeError: 'Buttons' object has no attribute '_shown'
  </code></pre>
  <p>My Python script:</p>
  <pre><code>import turtle
  
  wn = turtle.Screen()
  wn.bgcolor(&quot;black&quot;)
  wn.setup(width=800, height=600)
  wn.tracer(0)
  
  class Buttons(turtle.Turtle):
      def __init__(self, color, text):
          self.hideturtle()
          self.color(color)
          self.shape('square')
          self.shapesize(stretch_wid=3, stretch_len=7)
          self.penup()
          self.goto(0, 0)
          self.stamp()
          self.color('white')
          self.goto(0, 0 - FONT_SIZE/2)
          self.write(text, align='center', font=FONT)
  
  
  t1 = Buttons(&quot;green&quot;, &quot;start&quot;)
  
  while True:
      wn.update()
  </code></pre>