I am trying to use Tkinter to build a simple GUI app which imports data and performs some analysis. The GUI has just four labels and four buttons side by side. When you press the button, you should get a File Dialog prompt. However, whenever I run the script (see below), Python calls all button commands at startup, and then the buttons don't work afterwards. Even if I write the code without a class, the same thing happens. How do I get it to stop...