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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def has_archiver_index(config, archiver):
 """ Check if this archiver has an index file. :param config: The configuration :type config: :class:`wily.config.WilyConfig` :param archiver: The name of the archiver type (e.g. 'git') :type archiver: ``str`` :return: the exist :rtype: ``bool`` """

    root = pathlib.Path(config.cache_path) / archiver / "index.json"
    return root.exists()