def list_archivers(config):
root = pathlib.Path(config.cache_path)<EOL>result = []<EOL>for name in ALL_ARCHIVERS.keys():<EOL><INDENT>if (root / name).exists():<EOL><INDENT>result.append(name)<EOL><DEDENT><DEDENT>return result<EOL>
List the names of archivers with data.

:param config: The configuration
:type  config: :class:`wily.config.WilyConfig`

:return: A list of archiver names
:rtype: ``list`` of ``str``