如何使QSlider指示当前值

from PyQt5.QtWidgets import QApplication, QMainWindow, QSlider, QLabel, QVBoxLayout, QWidget
from PyQt5.QtCore import Qt

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("QSlider示例")
        self.setGeometry(100, 100, 300, 200)

        layout = QVBoxLayout()
        widget = QWidget()
        widget.setLayout(layout)
        self.setCentralWidget(widget)

        self.slider = QSlider(Qt.Horizontal)
        self.slider.setRange(0, 100)
        self.slider.setValue(50)
        self.slider.setSingleStep(1)
        self.slider.valueChanged.connect(self.update_label)

        self.label = QLabel("当前值: 50")

        layout.addWidget(self.slider)
        layout.addWidget(self.label)

    def update_label(self, value):
        self.label.setText("当前值: {}".format(value))

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