PyQt5 QTabWidget:如何在类中包含的选项卡和同一窗口中的选项卡之间切换？

from PyQt5.QtWidgets import QApplication, QMainWindow, QTabWidget, QWidget, QVBoxLayout, QLabel, QPushButton

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Tab Widget Example")
        self.setGeometry(100, 100, 400, 300)
        self.initUI()

    def initUI(self):
        self.tab_widget = QTabWidget(self)
        self.setCentralWidget(self.tab_widget)

        tab1 = QWidget()
        tab2 = QWidget()

        self.tab_widget.addTab(tab1, "Tab 1")
        self.tab_widget.addTab(tab2, "Tab 2")

        layout1 = QVBoxLayout()
        label1 = QLabel("This is Tab 1")
        button1 = QPushButton("Button 1")
        layout1.addWidget(label1)
        layout1.addWidget(button1)
        tab1.setLayout(layout1)

        layout2 = QVBoxLayout()
        label2 = QLabel("This is Tab 2")
        button2 = QPushButton("Button 2")
        layout2.addWidget(label2)
        layout2.addWidget(button2)
        tab2.setLayout(layout2)

if __name__ == "__main__":
    app = QApplication([])
    window = MainWindow()
    window.show()
    app.exec_()