#   self = cls()
    #   ax_args = success_response.extensionResponse(self.ns_uri, signed)
    def extensionResponse(self, namespace_uri, require_signed):
        """Return response arguments in the specified namespace.

        @param namespace_uri: The namespace URI of the arguments to be
        returned.

        @param require_signed: True if the arguments should be among
        those signed in the response, False if you don't care.

        If require_signed is True and the arguments are not signed,
        return None.
        """
        if require_signed:
            return self.getSignedNS(namespace_uri)
        else:
            return self.message.getArgs(namespace_uri)