<filename>mnemopy/main.py
import sys
from PyQt5 import QtWidgets
from .mnemopy import Ui_main_window

def main():
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_main_window()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

<filename>mnemopy/main.py
import sys
from PyQt5 import QtWidgets
from .mnemopy import Ui_main_window

def main():
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_main_window()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()
