def generate_authors(input_file):
    """
    Return authors fragment.

    Supports one or more authors, each with an optional url indicating their homepage.
    """
    authors = []

    for i in input_file['authors']:
        name = i['name']
        url = i['url']
        author = '[{name}]({url})'.format(name=name, url=url) if url else name
        authors.append(author)

    return ', '.join(authors)