ImiportError class not defined

[iFunKtion]

So I have tried to create another class in the main folder, but I still can't seem to access the widgets in the ui classes. Obviously, I can't just create an instance of the class, because the data is in the window that is currently active. So when I try to access the class directly, it just spits out the error that my SetupWidget Class has no attribute 'ui_get_client' which is the name of the field in the form I have made. How do I get this data out of here so that I can then set one of the labels in the main window?