title: Optimal tkinter file structure
body: <p>I'd like to divide my tkinter project into two files, let's call them GUI.py and backend.py.</p>
  <p>GUI.py will contain all the widgets definitions, while backend.py will contain the functions binded to the widgets. The problem is that in GUI.py I need to import backend.py in order to have access to the funtions while defining a widget (e.g. <code>button = tk.Button(...,command=myFun)</code>, where myFun is defined in backend.py), while in backend.py I need to import GUI.py to access some eventual input boxes (e.g. <code>text = myBox.get()</code>, where myBox is defined in GUI.py). Beside the fact that this is kinda cumbersome, the code won't execute if written in this way.</p>
  <p>What is the best way to divide the GUI from the backend?
  Thank you!</p>