howeverwhen getbuttonclicked(returns noneit means that the coordinates that were passed to it were not over any of the four buttons to make it clear that in this case the value none is returned from getbuttonclicked()we have the return none line at the end of the function to make your code more readableit is better to have your code be explicit (that isclearly state something even if it might be obviousrather than implicit (that isleaving it up to the person reading code to know how it works without outright telling themin fact--explicit is better than implicit|is one of the python koans the koans are group of little sayings about how to write good code there' an easter egg (that isa little hidden surprisein the python interactive shell where if you try to import module named thisthen it will display --the zen of python|koans try it out in the interactive shellimport this the zen of pythonby tim peters beautiful is better than ugly explicit is better than implicit simple is better than complex complex is better than complicated flat is better than nested sparse is better than dense readability counts special cases aren' special enough to break the rules although practicality beats purity errors should never pass silently unless explicitly silenced in the face of ambiguityrefuse the temptation to guess there should be one-and preferably only one --obvious way to do it although that way may not be obvious at first unless you're dutch now is better than never although never is often better than *rightnow if the implementation is hard to explainit' bad idea if the implementation is easy to explainit may be good idea namespaces are one honking great idea -let' do more of thoseif you' like to know more about what these individual koans meanvisit email questions to the authoral@inventwithpython com