How to use the betelgeuse.parser.HTMLWriter function in Betelgeuse

return ''
    if not hasattr(_register_roles, '_roles_registered'):
        _register_roles()
        _register_roles._roles_registered = True

    warning_stream = StringIO()
    parts = publish_parts(
        string,
        reader=NoDocInfoReader(),
        settings_overrides={
            'embed_stylesheet': False,
            'input_encoding': 'utf-8',
            'syntax_highlight': 'short',
            'warning_stream': warning_stream,
        },
        writer=HTMLWriter(translator_class=translator_class),
    )

    rst_parse_messages = []
    for warning in warning_stream.getvalue().splitlines():
        if not warning or ':' not in warning:
            continue
        warning = warning.split(' ', 2)
        rst_parse_messages.append(RSTParseMessage(
            line=warning[0].split(':')[1],
            level=warning[1].split('/')[0][1:].lower(),
            message=warning[2],
        ))
    warning_stream.close()

    # TODO: decide what to do with the rst parser warnings and errors
    return parts['html_body']