在PyQt5中如何控制窗口关闭按钮事件？

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QMessageBox

class MyWindow(QWidget):
    def __init__(self):
        super().__init__()

    def closeEvent(self, event):
        reply = QMessageBox.question(self, '提示', '确定要关闭窗口吗？', QMessageBox.Yes | QMessageBox.No, QMessageBox.No)
        if reply == QMessageBox.Yes:
            event.accept()
        else:
            event.ignore()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MyWindow()
    window.show()
    sys.exit(app.exec_())