def sanitize_svg(svg):
    """ I couldn't find a good svg sanitiser function yet, so for now
    this function will be a no-op, though it will try to detect
    svg files which are harmful.

    I tried to go with bleach/html5lib, but the lack of xml namespace support
    makes those options a no go.

    In the future we want a proper SVG sanitiser here!

    """
    assert 'javascript:' not in svg
    assert 'CDATA' not in svg
    assert '<script>' not in svg
    assert 'Set-Cookie' not in svg
    return svg
