code: def trim(self):
          
          # Only allow leaves to stay on list (highest-resolution) level
          return
  
          for l in self._levels[-2::-1]:
              for n in l:
                  if n.is_leaf:
                      n.parent.remove_child(n.label)
  
          self._clear_all_leaves()
docs: Trims leaves from tree that are not observed at highest-resolution level
  
          This is a bit hacky-- what it does is