code: def indexbox(msg="Shall I continue?"
      , title=" "
      , choices=("Yes","No")
      , image=None
      ):
      
      reply = buttonbox(msg=msg, choices=choices, title=title, image=image)
      index = -1
      for choice in choices:
          index = index + 1
          if reply == choice: return index
      raise AssertionError(
          "There is a program logic error in the EasyGui code for indexbox.")
docs: Display a buttonbox with the specified choices.
      Return the index of the choice selected.