def get_header(self):
        """Get the header value from the response.

        :return: a future contains the deserialized value of header
        """
        raw_header = yield get_arg(self, 1)
        if not self.serializer:
            raise tornado.gen.Return(raw_header)
        else:
            header = self.serializer.deserialize_header(raw_header)
            raise tornado.gen.Return(header)