docs: function authenticate(req, cb) {
      request.post(
        'https://github.com/login/oauth/access_token',
        { form:
          { client_id: process.env.GHID,      // don't store credentials in opts
            client_secret: process.env.GHCS,  // get them straight from process.env
            code: req.query.code } },
        function(err, resp, body) {
          if (err) return cb(err);
          var result = qs.parse(body);
          getUser(req, result, function() {
            cb(null, result);
          });
        }
      );
    }