def on_cleanup_error(function, path, excinfo):
                click.secho("warning: failed to remove file or directory: {}\n"
                            "please delete it manually.".format(path),
                            fg="red")
def memoized(*args):
        try:
            return stored_results[args]
        except KeyError:
            result = stored_results[args] = fn(*args)
            return result