Signals code problem

q&a
,
1

I have to add:

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

and changed:

class MainWindow(QtWidgets.QMainWindow):

to

class MainWindow(QMainWindow):

and add:

app = QApplication(sys.argv)

window = MainWindow()
window.show()

app.exec_()

for this example to work.