code: def _set_location(instance, location):
      
      location = str(location)
      if not location.startswith('/'):
          location = urljoin(instance.request_path.rstrip('/') + '/', location)
      instance.response.location = location
docs: Sets a ``Location`` response header. If the location does not start with
      a slash, the path of the current request is prepended.
  
      :param instance: Resource instance (used to access the request and
                       response)
      :type instance: :class:`webob.resource.Resource`