def with_port(url_str):
    """ Adds to an URL the port from the settings
        useful for development

        >>> with_port("http://localhost/ddd")
        'http://localhost:8000/ddd'
        >>> with_port("localhost/ddd")
        'localhost/ddd'
    """
    try:
        port = settings.PORT
    except AttributeError:
        port = None
    if port == 80:
        port = None
    url_split = urlsplit(url_str)
    if port:
        if not url_split.port and url_split.netloc:
            scheme, netloc, url, query, fragment = url_split
            netloc += ":%s" % port
            url_split = SplitResult(scheme, netloc, url, query, fragment)
    return url_split.geturl()