Should I use `app.exec()` or `app.exec_()` in my PyQt application?
That’s because until Python 3, exec was a reserved keyword, so the PyQt devs added underscore to it. From Python 3 onwards, exec is no longer a reserved keyword (because it is a builtin function; same situation as print), so it made sense in PyQt5 to provide a version without an underscore to be consistent … Read more