text: import typing
  from PySide2.QtWidgets import QMainWindow, QApplication
  
  
  def findMainWindow() -> typing.Union[QMainWindow, None]:
      # Global function to find the (open) QMainWindow in application
      app = QApplication.instance()
      for widget in app.topLevelWidgets():
          if isinstance(widget, QMainWindow):
              if getattr(widget, 'identifier', None) == "MainWindow":
                  return widget
  
      return None
  