PyCalculator/main.py

import sys
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.uic import *
from Calculator import Calculator

if __name__ == "__main__":
    app = QApplication(sys.argv)
    calculator = Calculator(title='Calculator', parent=None,
                            uiFile='form/ui_calculator.ui')
    app.exec_()