Python: Is there something like waitbar of matlab?

Question

my situation is: I have a for loop in which simulations are done and it takes around 2 days until it is finished. Therefore I want to implement a GUI with a progressbar. In MATLAB I used waitbar.

But how do I do this in Python? My aim is that the progressbar is updated after each iteration. But I dont want to use multithreading because that would be wastage(only one information is updated every 2 or 3 minutes). So the GUI should kept open in the background and after each iteration the progressbar should be updated. I hope you understand what I mean.

    start progressbar

    for k in range(2000)

        update progressbar
        .
        .
        simulation is done
        .
        .
    close progressbar

So this should be done without multithreading. I know how I build the GUI with the progressbar, but I dont know how I can update it.

Thanks for your help!!