title: How to change size of turtle?
body: <p>I am trying to double the size of the turtle in the window every time I press <code>x</code> on my keyboard. I tried using <code>.turtlesize(2,2,2)</code>, but that's not right. I need to double every time the key is pressed so if the turtle size is <code>(1,1,1)</code>, it will become <code>(2,2,2)</code> then <code>(4,4,4)</code> and so on each time I press <code>x</code>. </p>
  
  <p>This is what I have so far:</p>
  
  <pre><code>import turtle
  turtle.setup(500,500)
  wn = turtle.Screen()
  wn.title("Commands")
  wn.bgcolor("black")
  
  tess = turtle.Turtle()
  tess.shape("triangle")
  tess.color("red")
  tess.left(90)
  
  def increaseSize():
      size = tess.turtlesize()
      increase = tuple([2 * num for num in size])
      tess.turtlesize(increase) #this is where the error occurs
  
  wn.onkey(increaseSize, "x")
  wn.listen()
  </code></pre>