Etiqueta PyQt5: acceso al nivel de opacidad del efecto de opacidad

# importing libraries
from PyQt5.QtWidgets import * 
from PyQt5 import QtCore, QtGui
from PyQt5.QtGui import * 
from PyQt5.QtCore import * 
import sys
  
  
class Window(QMainWindow):
  
    def __init__(self):
        super().__init__()
  
        # setting title
        self.setWindowTitle("Python ")
  
        # setting geometry
        self.setGeometry(100, 100, 600, 400)
  
        # calling method
        self.UiComponents()
  
        # showing all the widgets
        self.show()
  
    # method for widgets
    def UiComponents(self):
  
        # creating label
        label = QLabel("Label", self)
  
        # setting geometry to the label
        label.setGeometry(200, 100, 150, 60)
  
        # setting alignment to the label
        label.setAlignment(Qt.AlignCenter)
  
        # setting font
        label.setFont(QFont('Arial', 15))
  
        # setting style sheet of the label
        label.setStyleSheet("QLabel"
                            "{"
                            "border : 2px solid green;"
                            "background : lightgreen;"
                            "}")
  
        # creating a opacity effect
        self.opacity_effect = QGraphicsOpacityEffect()
  
        # setting opacity level
        self.opacity_effect.setOpacity(0.3)
  
        # adding opacity effect to the label
        label.setGraphicsEffect(self.opacity_effect)
  
        # result label
        result = QLabel(self)
  
        # setting geometry of the result label
        result.setGeometry(200, 200, 300, 30)
  
        # getting opacity level
        level = self.opacity_effect.opacity()
  
        # setting text to the result label
        result.setText("Opacity level : " + str(level))
  
  
# create pyqt5 app
App = QApplication(sys.argv)
  
# create the instance of our Window
window = Window()
  
# start the app
sys.exit(App.exec())