human
Complete this python program:
def _refresh_buckets_cache_file(creds, cache_file, multiple_env, environment, prefix):
assistant
#Here is the Python code you requested.

    """Retrieve the content of all buckets and cache the metadata to the buckets
    cache file
    """
    def __get_s3_meta():
        return __utils__['s3.query'](key=creds.key, keyid=creds.keyid, kms_keyid=creds.kms_keyid, bucket=creds.bucket, service_url=creds.service_url, verify_ssl=creds.verify_ssl, location=creds.location, return_bin=False, params={'prefix': prefix}, path_style=creds.path_style, https_enable=creds.https_enable)
    def __get_pillar_files_from_s3_meta(s3_meta):
        return [k for k in s3_meta if ('Key' in k)]
    def __get_pillar_environments(files):
        environments = [os.path.dirname(k['Key']).split('/', 1)[0] for k in files]
        return set(environments)
    log.debug('Refreshing    S3    buckets    pillar    cache    file')
    metadata = {}
    bucket = creds.bucket
    if (not multiple_env):
        log.debug('Single    environment    per    bucket    mode')
        bucket_files = {}
        s3_meta = __get_s3_meta()
        if s3_meta:
            bucket_files[bucket] = __get_pillar_files_from_s3_meta(s3_meta)
            metadata[environment] = bucket_files
    else:
        log.debug('Multiple    environment    per    bucket    mode')
        s3_meta = __get_s3_meta()
        if s3_meta:
            files = __get_pillar_files_from_s3_meta(s3_meta)
            environments = __get_pillar_environments(files)
            for saltenv in environments:
                env_files = [k for k in files if k['Key'].startswith(saltenv)]
                if (saltenv not in metadata):
                    metadata[saltenv] = {}
                if (bucket not in metadata[saltenv]):
                    metadata[saltenv][bucket] = []
                metadata[saltenv][bucket] += env_files
    if os.path.isfile(cache_file):
        os.remove(cache_file)
    log.debug('Writing    S3    buckets    pillar    cache    file')
    with salt.utils.files.fopen(cache_file, 'w') as fp_:
        pickle.dump(metadata, fp_)
    return metadata