title: tkinter setting default checkbox to being checked returns value as "checked"
body: <p>This is my code: </p>
  
  <pre><code>master = Tk()  
  var1 = IntVar(master) 
  var1.set(1) 
  Checkbutton(master, text = 'check', variable = var1)
  Button(text = 'submit', command = master.quit') 
  check = var1.get() 
  </code></pre>
  
  <p>It sets the default to being checked, but even when I uncheck it on the GUI and hit submit, the value of check is still 1. </p>
  
  <p>Why is the action of unchecking the checkbox not being registered? </p>