def create_return_url(base, query, **kwargs):
    """
    Add a query string plus extra parameters to a base URL which may contain
    a query part already.

    :param base: redirect_uri may contain a query part, no fragment allowed.
    :param query: Old query part as a string
    :param kwargs: extra query parameters
    :return:
    """
    part = urlsplit(base)
    if part.fragment:
        raise ValueError("Base URL contained parts it shouldn't")

    for key, values in parse_qs(query).items():
        if key in kwargs:
            if isinstance(kwargs[key], basestring):
                kwargs[key] = [kwargs[key]]
            kwargs[key].extend(values)
        else:
            kwargs[key] = values

    if part.query:
        for key, values in parse_qs(part.query).items():
            if key in kwargs:
                if isinstance(kwargs[key], basestring):
                    kwargs[key] = [kwargs[key]]
                kwargs[key].extend(values)
            else:
                kwargs[key] = values

        _pre = base.split("?")[0]
    else:
        _pre = base

    logger.debug("kwargs: %s" % kwargs)

    return "%s?%s" % (_pre, url_encode_params(kwargs))
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/pysaml2-2.4.0/src/saml2/authn.py/create_return_url/original