text: 
  #!/usr/bin/python3
  # -*- coding: utf-8 -*-
  
  """
  ZetCode PyQt5 tutorial 
  
  This program shows a confirmation 
  message box when we click on the close
  button of the application window. 
  
  author: Jan Bodnar
  website: zetcode.com 
  last edited: January 2015
  """
  
  import sys
  from PyQt5.QtWidgets import QWidget, QMessageBox, QApplication
  
  
  class Example(QWidget):
      
      def __init__(self):
          super().__init__()
          
          self.initUI()
          
          
      def initUI(self):               
          
          self.setGeometry(300, 300, 250, 150)        
          self.setWindowTitle('Message box')    
          self.show()
          
          
      def closeEvent(self, event):
          
          reply = QMessageBox.question(self, 'Message',
              "Are you sure to quit?", QMessageBox.Yes | 
              QMessageBox.No, QMessageBox.No)
  
          if reply == QMessageBox.Yes:
              event.accept()
          else:
              event.ignore()        
          
          
  if __name__ == '__main__':
      
      app = QApplication(sys.argv)
      ex = Example()
      sys.exit(app.exec_())
  