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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 koschei_group(config, message, group=None):
 """ Particular Koschei package groups This rule limits message to particular `Koschei <https://apps.fedoraproject.org/koschei/>`_ groups. You can specify more groups separated by commas. """

    if not group or 'koschei' not in message['topic']:
        return False
    groups = set([item.strip() for item in group.split(',')])
    return bool(groups.intersection(message['msg'].get('groups', [])))