def _enumerate_paths(self, prefix_path):
        """
        Recursive (private) part of :func:`enumerate_paths`. Returns generator
        of recursive lists of two items, where second item is the branch object
        and first one is itself list of two items.
        """
        for branch in self.branches:
            path = [prefix_path, branch]
            if branch.child_branchset is not None:
                for subpath in branch.child_branchset._enumerate_paths(path):
                    yield subpath
            else:
                yield path
Recursive (private) part of :func:`enumerate_paths`. Returns generator
        of recursive lists of two items, where second item is the branch object
        and first one is itself list of two items.