title: turtle.onclick() doesn't work as supposed to
body: <p>I have a script for a simple turtle race and I want the race to start when the user clicks the left-mouse-button so i have this code </p>
  
  <pre><code>def tur_race():
      for step in range(0, 135):
          tur1.forward(randint(1, 5))
          tur2.forward(randint(1, 5))
  
  
  turtle.pu()
  turtle.goto(-250, -150)
  turtle.write("click the mouse to start")
  turtle.ht()
  turtle.onscreenclick(tur_race())
  turtle.mainloop()
  </code></pre>
  
  <p>Assume that I have all variables defined.</p>
  
  <p>when I run this code the race starts automatically and doesn't wait for the click.</p>