# File lib/openid/message.rb, line 196
    def set_openid_namespace(openid_ns_uri, implicit)
      if !@@allowed_openid_namespaces.include?(openid_ns_uri)
        raise InvalidOpenIDNamespace, "Invalid null namespace: #{openid_ns_uri}"
      end
      @namespaces.add_alias(openid_ns_uri, NULL_NAMESPACE, implicit)
      @openid_ns_uri = openid_ns_uri
    end