def create_metadata(title, comment='', author=None):
    """Creates metadata for video.

    Args:
        title (string): title of the video
        comment (string): comment of the video
        author (strin): author of the video

    Returns:
        dict
    """
    author = 'https://github.com/narimiran' if author is None else author
    return dict(artist=author, title=title, comment=comment)