def login(self):
    global username
    global password
    msgBox = QtWidgets.QMessageBox()
    msgBox.setIcon(QtWidgets.QMessageBox.Warning)
    msgBox.setWindowTitle("Error")
    try:
        userLogin = self.userBox.text()
        passwordLogin = self.passwordBox.text()
        if not userLogin or not passwordLogin:
            msgBox.setText("Ooops, Please enter an acceptible username and/or password.")
            msgBox.exec()
            self.userBox.clear()
            self.passwordBox.clear()
        elif userLogin == " " or passwordLogin == " ":
            msgBox.setText("Ooops, Please enter an acceptible username and/or password.")
            msgBox.exec()
            self.userBox.clear()
            self.passwordBox.clear()
        else:
            username = userLogin
            password = passwordLogin
            self.close()
            self.w = MainWindow()
            self.w.show()
    except (ValueError, TypeError) as e:
        msgBox.setText("Ooops, {}. Please enter an acceptible username and/or password.".format(e))
        msgBox.exec()
        self.userBox.clear()
        self.passwordBox.clear()