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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 _get_cache_dir():
    '''
    Get pillar cache directory. Initialize it if it does not exist.
    '''

    cache_dir = os.path.join(__opts__['cachedir'], 'pillar_s3fs')

    if not os.path.isdir(cache_dir):
        log.debug('Initializing S3 Pillar Cache')
        os.makedirs(cache_dir)

    return cache_dir