Импорт функций в Python+Qtdesigner

from inter_main_window import *
import sys
import os
 
app = QtWidgets.QApplication(sys.argv)
MainWindow = QtWidgets.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
 
 
def onClicked():
 
    os.system('int_2_form.py')
 
ui.pushButton.clicked.connect(onClicked) #Открыть окно для ввода данных в БД
 
def Old_bd():
    pass
sys.exit(app.exec_())

from int_2_form import *
from main_window import onClicked() #Пробовал импортировать таким образом
import sys
from openpyxl import load_workbook
 
app = QtWidgets.QApplication(sys.argv)
MainWindow = QtWidgets.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
def write_new_data():
    DATE_data=ui.lineEdit.text()
    ADRES_data=ui.lineEdit_2.text()
    S_data = ui.lineEdit_3.text()
    Tehnika_data = ui.lineEdit_4.text()
 
    fn="new_base.xlsx"
    wb=load_workbook(fn)
    ws=wb["Лист1"]
    ws.append([DATE_data,ADRES_data,S_data,Tehnika_data])
    wb.save(fn)
    wb.close()
 
ui.pushButton2.clicked.connect(write_new_data)
 
 
 
sys.exit(app.exec_())

def foo(message: str) -> None:
    print(message)

from parent import foo
 
foo("Hello, World!")

import parent
 
parent.foo("Hello, World!")