Python，Tkinter库，涉及GUI的对象中的属性错误

I'm making a very simple program for class that involves multiplying the number of a GUI slider by another number of another GUI slider. But, for some reason when I run the program now, I get an AttributeError saying that 'gui' object has no attribute 'slider1'. Any ideas? Here's the code:I'm making a very simple program for class that