How to use the treq.auth.add_auth function in treq

headers.setRawHeaders(
                    'content-type', ['application/x-www-form-urlencoded'])
                data = urlencode(data, doseq=True)
            bodyProducer = IBodyProducer(data)

        wrapped_agent = self._agent

        if kwargs.get('allow_redirects', True):
            wrapped_agent = RedirectAgent(wrapped_agent)

        wrapped_agent = ContentDecoderAgent(wrapped_agent,
                                            [('gzip', GzipDecoder)])

        auth = kwargs.get('auth')
        if auth:
            wrapped_agent = add_auth(wrapped_agent, auth)

        d = wrapped_agent.request(
            method, url, headers=headers,
            bodyProducer=bodyProducer)

        timeout = kwargs.get('timeout')
        if timeout:
            delayedCall = default_reactor(kwargs.get('reactor')).callLater(
                timeout, d.cancel)

            def gotResult(result):
                if delayedCall.active():
                    delayedCall.cancel()
                return result

            d.addBoth(gotResult)

cookies = merge_cookies(self._cookiejar, cookies)
        wrapped_agent = CookieAgent(self._agent, cookies)

        if kwargs.get('allow_redirects', True):
            if kwargs.get('browser_like_redirects', False):
                wrapped_agent = BrowserLikeRedirectAgent(wrapped_agent)
            else:
                wrapped_agent = RedirectAgent(wrapped_agent)

        wrapped_agent = ContentDecoderAgent(wrapped_agent,
                                            [(b'gzip', GzipDecoder)])

        auth = kwargs.get('auth')
        if auth:
            wrapped_agent = add_auth(wrapped_agent, auth)

        d = wrapped_agent.request(
            method, url, headers=headers,
            bodyProducer=bodyProducer)

        timeout = kwargs.get('timeout')
        if timeout:
            delayedCall = default_reactor(kwargs.get('reactor')).callLater(
                timeout, d.cancel)

            def gotResult(result):
                if delayedCall.active():
                    delayedCall.cancel()
                return result

            d.addBoth(gotResult)