'Create a redirect object with the dest_uri, which may be relative,
considering it relative to the uri implied by the given environ.'

def relative_redirect(cls, dest_uri, environ, detail=None, headers=None, comment=None):

    location = resolve_relative_url(dest_uri, environ)
    headers = (headers or [])
    headers.append(('Location', location))
    return cls(detail=detail, headers=headers, comment=comment)
