How would get gain access to successF and errorF?

angular service example.js

service.factory('userService', [
    '$http',
    function($http) {

      return {
        name : 'User Service',
        request : {},
        successF : {},
        errorF : {},

        login : function(user) {
          this.successF = {};
          this.errorF = {};
          this.request = {
            method : 'POST',
            url : '/api/login',
            data : user
          };
          return this;
        },

        success : function(func) {
          this.successF = func;
          return this;
        },

        error : function(func) {
          this.errorF = func;
          return this;
        },

        go : function() {
          console.log('Executing ' + this.request);
          $http(this.request).success(function(data, status, headers, config) {
            successF(data, status, headers, config);
          }).error(function(data, status, headers, config) {
            errorF(data, status, headers, config);
          });
        }

      };

    } ]);

In the final 'go' function, I can't get access to the successF and the errorF

Here's how I'm trying to call the service...

    userService.login(user).success(function(data, status) {
      $scope.status = status;
      $scope.closeLoginDialog();
      $window.location.reload();
    }).error(function(data, status) {
      $scope.status = status;
      $scope.errorMsg = data;
    }).go();