def _tempDirectories(self):
        """
        :rtype : an iterator to the temporary directories containing jobs/stats files
        in the hierarchy of directories in self.tempFilesDir
        """
        def _dirs(path, levels):
            if levels > 0:
                for subPath in os.listdir(path):
                    for i in _dirs(os.path.join(path, subPath), levels-1):
                        yield i
            else:
                yield path
        for tempDir in _dirs(self.tempFilesDir, self.levels):
            yield tempDir