I'm just a beginner. How to put other ui file into existing frame

[creeper82]

I don't know what hit me to make this in python, but I want to make a simple gui for a home raspberry pi information device. Well the ui is something that doesn't make problems for me. However I'm bad in python especially that I've never learned it and just done the project only looking through examples. Now here's a Problem. Im using that typical code with class i called gui and init with creating the builder and importing ui file. Now let's say at the bottom of ui there are 3 buttons to switch one frame (frame_4) in my case to display a small information. So as I said I'm new to Python and I have no idea on how to access the builder from callback function after pressing that button. The function is outside gui class. And from there I want to put UI file into a frame that is already existing in created window at start. Normally I would just ask how to get access to builder, but I also have no idea on how to import UI to existing frame. Sorry for no code, I can post image because I'm on my phone and weird things are happening with github on my PC. I can send the code because ui file doesn't fit in one image And I'll remove some of useless imports later. I hope anyone understands me there. Thank you.