How to use the simple-get.concat function in simple-get

function loadReleases (cb) {
  const opts = {
    url: 'https://api.github.com/repos/webtorrent/webtorrent-desktop/releases',
    json: true,
    timeout: 30 * 1000,
    headers: {
      'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36'
    }
  }

  console.log('Fetching ' + opts.url)
  get.concat(opts, function (err, res, data) {
    if (err) return cb(err)
    console.log('Got ' + data.length + ' WebTorrent Desktop releases')
    const releases = data.map(function (d) {
      // Count total downloads
      let win32 = 0
      let darwin = 0
      let linux = 0
      d.assets.map(function (a) {
        if (a.name.endsWith('.dmg')) {
          darwin += a.download_count
        } else if (a.name.endsWith('.exe')) {
          win32 += a.download_count
        } else if (a.name.endsWith('.deb') ||
                   a.name.endsWith('linux-ia32.zip') ||
                   a.name.endsWith('linux-x64.zip')) {
          linux += a.download_count

login (cb) {
    // Check that required params exist
    if (typeof cb !== 'function') {
      throw new Error('Invalid or missing `cb` parameter for login method')
    }

    const requestData = {
      url: TW_REQ_TOKEN_URL,
      method: 'POST',
      data: {
        oauth_callback: this.callbackUrl
      }
    }

    // Get a "request token"
    get.concat({
      url: requestData.url,
      method: requestData.method,
      form: requestData.data,
      headers: this._oauth.toHeader(this._oauth.authorize(requestData))
    }, (err, res, data) => {
      if (err) return cb(err)

      const {
        oauth_token: token,
        oauth_token_secret: tokenSecret,
        oauth_callback_confirmed: callbackConfirmed
      } = querystring.parse(data.toString())

      // Must validate that this param exists, according to Twitter docs
      if (callbackConfirmed !== 'true') {
        return cb(new Error('Missing `oauth_callback_confirmed` parameter in response'))

commonTest.createServer(t, 'http', function (server, announceUrl) {
    var url = announceUrl.replace('/announce', '/stats')

    get.concat(url, function (err, res, data) {
      t.error(err)

      var stats = parseHtml(data.toString())
      t.equal(res.statusCode, 200)
      t.equal(stats.torrents, 0)
      t.equal(stats.activeTorrents, 0)
      t.equal(stats.peersAll, 0)
      t.equal(stats.peersSeederOnly, 0)
      t.equal(stats.peersLeecherOnly, 0)
      t.equal(stats.peersSeederAndLeecher, 0)
      t.equal(stats.peersIPv4, 0)
      t.equal(stats.peersIPv6, 0)

      server.close(function () { t.pass('server closed') })
    })
  })

return done(err);
            }

            if (!shows.length) {
                return done();
            }

            getLatest(shows[0].id, distance, done);
        });
    } else {
        id = series;
    }

    url = exports.host + '/watch-' + id + '-X-online-free';

    get.concat(url, function (err, res, body) {
        var $, episode, match;

        if (err) {
            return done(err);
        }

        try {
            $ = cheerio.load(body);
        } catch (e) {
            return done(e);
        }

        episode = $('.tv_episode_item a').get();
        episode = episode[episode.length - distance];

        if (!episode || !episode.attribs || !episode.attribs.href) {

function search(terms, done) {
    get.concat(exports.host + '?' + qs.encode({
        'search_keywords': terms.title,
        'search_section': terms.section === 'tv' ? 2 : 1,
        key: '',
        year: terms.year,
        page: 1
    }), function (err, res, body) {
        var $, shows;

        if (err) {
            return done(err);
        }

        try {
            $ = cheerio.load(body);
        } catch (e) {
            return done(e);

return new Promise(function (resolve, reject) {
    log('getting from url', url);
    simpleGet.concat(url, function (err, data, res) {
      if (err) {
        log('simple get error from url', url, err);
        return reject(err);
      }
      if (res.statusCode !== 200) {
        log('while fetching from', url, 'got', res.statusCode);
        log(res);
        return reject(new Error('GET from ' + url + ' status ' + res.statusCode));
      }
      return resolve(data);
    });
  });
}

api_key: this._key,
      format: 'json'
    })

    const urlBase = 'https://ws.audioscrobbler.com/2.0/'

    const opts = {
      url: urlBase + '?' + querystring.stringify(params),
      headers: {
        'User-Agent': this._userAgent
      },
      timeout: 30 * 1000,
      json: true
    }

    get.concat(opts, onResponse)

    function onResponse (err, res, data) {
      if (err) return cb(err)
      if (data.error) return cb(new Error(data.message))
      cb(null, data[name])
    }
  }