How can you call another window from the main one in pyqt5?

Question

PyQt

I have a main window in pyqt5 and I need to call another window file also written in pyqt5, there are some rules for this, because in the end I need to compile this into an EXE file. And the method calldoesn't work. Calling the import file window and calling the function does not work (mb I'm doing something wrong).