app.factory('AdvancedGithubUser', function($http, SimpleGithubUser) {
    var apiUrl = 'https://api.github.com/';

    // create new custom object that reuse the original object constructor
    var AdvancedGithubUser = function() {
        SimpleGithubUser.apply(this, arguments);
    };

    // reuse the original object prototype
    AdvancedGithubUser.prototype = Object.create(SimpleGithubUser.prototype);

    // define a new internal private method for this object
    function getUserEvents() {
        var self = this;
        return $http.get(apiUrl + 'users/' + this.username + '/events')
          .then(function(response) {

            // attach the events API result to our user profile
            self.profile.events = response.data;

            // promises should always return a result
            return response;
        });
    }

    // Now let's override our original getProfile method
    AdvancedGithubUser.prototype.getProfile = function() {

        var self = this;

        // we first call the original getProfile method (aka super method)
        var originalGetProfile = SimpleGithubUser.prototype.getProfile.apply(this, arguments);

        // we use promises chaining to add additional data
        return originalGetProfile.then(function() {

            // before returning the result,
            // call our new private method and bind "this" to "self"
            // we need to do this because the method is not part of the prototype
            return getUserEvents.call(self);
        });
    };
    return AdvancedGithubUser;
});

angular.isValue = function(val) {
  return !(val === null || !angular.isDefined(val) || (angular.isNumber(val) && !isFinite(val)));
};
angular.isUndefinedOrNull = function(val) {
  return angular.isUndefined(val) || val === null
}