def restore_downloads(torrent_client, params):
    """
    Restore partial torrent downloads, i.e. torrents in 'finished' state.

    params['info_hashes']: list of str - the list of info-hashes
    :return: 'OK'
    """
    for info_hash in params['info_hashes']:
        torrent_client.set_piece_priorities(info_hash, 1)
    return 'OK'