使用另一个文件中的类到我的第二个文件python3中的类的函数

I have two python files, one is the gui, the other contains all of the functions, say i have a class named Backend like in the code below, and one of its functions is "print1(self)", and i want to use that "print1" function inside of the second file in the class named retranslateUi(self, Form), how would i do it?I have two python files, one is the gui, the ot