code: def ynbox(msg="Shall I continue?"
      , title=" "
      , choices=("Yes", "No")
      , image=None
      ):
      
      return boolbox(msg, title, choices, image=image)
docs: Display a msgbox with choices of Yes and No.
  
      The default is "Yes".
  
      The returned value is calculated this way::
          if the first choice ("Yes") is chosen, or if the dialog is cancelled:
              return 1
          else:
              return 0
  
      If invoked without a msg argument, displays a generic request for a confirmation
      that the user wishes to continue.  So it can be used this way::
          if ynbox(): pass # continue
          else: sys.exit(0)  # exit the program
  
      @arg msg: the msg to be displayed.
      @arg title: the window title
      @arg choices: a list or tuple of the choices to be displayed