code: def flatten_all_paths(self, group_filter=lambda x: True,
                            path_filter=lambda x: True,
                            path_conversions=CONVERSIONS):
          
          return flatten_all_paths(self.tree.getroot(), group_filter,
                                   path_filter, path_conversions)
docs: Forward the tree of this document into the more general
          flatten_all_paths function and return the result.