code: def traverse_local_prefs(stepback=0):
      
      locals_dict = get_frame_locals(stepback+1)
      for k in locals_dict:
          if not k.startswith('_') and k.upper() == k:
              yield k, locals_dict
docs: Generator to walk through variables considered as preferences
      in locals dict of a given frame.
  
      :param int stepback:
  
      :rtype: tuple