code: def update_highlights(self, old_highlight_set, new_highlight_set):
          
          if not self.gui_up:
              return
  
          un_hilite_set = old_highlight_set - new_highlight_set
          re_hilite_set = new_highlight_set - old_highlight_set
  
          # unhighlight entries that should NOT be highlighted any more
          for key in un_hilite_set:
              self._highlight_path(key, False)
  
          # highlight new entries that should be
          for key in re_hilite_set:
              self._highlight_path(key, True)
docs: Unhighlight the entries represented by ``old_highlight_set``
          and highlight the ones represented by ``new_highlight_set``.
  
          Both are sets of keys.