QApplication — Qt for Python
https://doc.qt.io/qtforpython-5/PySide2/QtWidgets/QApplication.htmlQApplication specializes QGuiApplication with some functionality needed for QWidget-based applications.It handles widget specific initialization, finalization. For any GUI application using Qt, there is precisely one QApplication object, no matter whether the application has 0, 1, 2 or more windows at any given time. For non- QWidget based Qt applications, use QGuiApplication …