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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 ext_pillar(minion_id, pillar, conf):
    '''
    Return an existing set of certificates
    '''
    cache = salt.cache.Cache(__opts__, syspaths.CACHE_DIR)

    ret = {}
    dns_names = cache.fetch('venafi/minions', minion_id)
    for dns_name in dns_names:
        data = cache.fetch('venafi/domains', dns_name)
        ret[dns_name] = data
        del ret[dns_name]['csr']
    return {'venafi': ret}