title: "UnboundLocalError" When I try to use the tkinter Frame widget in python3?
body: <pre><code>master = Tk()
  title_frame = Frame(master, bg="yellow")
  Label(master, text="Sample Name").pack()
  master.mainloop()
  </code></pre>
  
  <p>When I try to use this code inside of a class method I get an error message stating "UnboundLocalError: local variable 'Frame' referenced before assginemt". I'm not sure how to fix this. The first time I ran this it worked fine, and then I tweaked some things in the code below these lines and it started giving me that error message. Interestingly about 10 lines down I create a frame in the exact same manner and it does not appear to raise an error messages.</p>