code: function FixedAgent(app, options) {
      if (!(this instanceof FixedAgent)) {
          return new FixedAgent(app, options);
      }
  
      Agent.call(this, app, options);
  }
docs: Initializes a new supertest agent which its _saveCookies method
  fixed to work with jest.
  @param {Function|Server} app
  @param {Object} options
  @returns {FixedAgent}
  @constructor
  @api public