pyqt5 QTimer.singleShot根本不运行

import sys
from PyQt5.QtCore import QTimer
from PyQt5.QtWidgets import QApplication, QMainWindow, QLabel

def my_function():
    print("QTimer.singleShot is running")

if __name__ == "__main__":
    app = QApplication(sys.argv)
    
    # 创建一个主窗口
    window = QMainWindow()
    window.setWindowTitle("QTimer.singleShot Example")
    
    # 创建一个标签
    label = QLabel(window)
    label.setText("Hello World")
    label.setGeometry(100, 100, 200, 50)
    
    # 在2秒后执行my_function函数
    QTimer.singleShot(2000, my_function)
    
    # 显示主窗口
    window.show()
    
    # 运行事件循环
    sys.exit(app.exec_())