code: function(options) {
        var model = this;
        options = options || {};
        var request = Parse._request({
          route: "login",
          method: "GET",
          useMasterKey: options.useMasterKey,
          data: this.toJSON()
        });
        return request.then(function(resp, status, xhr) {
          var serverAttrs = model.parse(resp, status, xhr);
          model._finishFetch(serverAttrs);
          model._handleSaveResult(true);
          return model;
        })._thenRunCallbacks(options, this);
      }
docs: Logs in a Parse.User. On success, this saves the session to localStorage,
  so you can retrieve the currently logged in user using
  <code>current</code>.
  
  <p>A username and password must be set before calling logIn.</p>
  
  <p>Calls options.success or options.error on completion.</p>
  
  @param {Object} options A Backbone-style options object.
  @see Parse.User.logIn
  @return {Parse.Promise} A promise that is fulfilled with the user when
  the login is complete.