def METHOD_NAME(url, md5sum, target_dir, manifest_path):
    """Download, unpack and create summmary manifest file.
    """
    if not os.path.exists(os.path.join(target_dir, "LibriSpeech")):
        # download
        filepath = download(url, md5sum, target_dir)
        # unpack
        unpack(filepath, target_dir)
    else:
        print("Skip downloading and unpacking. Data already exists in %s." %
              target_dir)
    # create manifest json file
    create_manifest(target_dir, manifest_path)