import sys
import readergui as rg

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

class Window(QMainWindow):
    def __init__(self):
        super(Window, self).__init__()
        self.ui = rg.Ui_MainWindow()
        self.ui.setupUi(self)
        self.ui.nextButton.clicked.connect(self.but_test)
    def but_test(self):
         print("button clicked")

if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = Window()
    window.show()
    sys.exit(app.exec())