// Пример создания задачи
        public void RequestDataFromServer(TaskListReadingCallback callback, ErrorCallback errorCallback)
        {
            _readingCallback      = callback;
            _readingErrorCallback = errorCallback;

            FindServer();
            _timerPlannedActions.Enqueue(new PlannedAction(SendRefreshRequestWaiter, DefaultTimeout));
        }
        public void RequestDataFromServer(TaskListReadingCallback callback)
        {
            _readingCallback = callback;
            // TODO Retreiving task list from tutor's server

            // Placeholder
            Category rootCategory = new Category();

            rootCategory.Name        = "ROOT";
            rootCategory.Description = "Root category should not be displayed to user";
            Category integralsSubCat = new Category();

            // Integrals demo
            integralsSubCat.Name        = "Integrals";
            integralsSubCat.Description = "Various exercises related to integral equations";
            LearningTask taskInt1 = new LearningTask
            {
                Name     = "Task 1",
                TaskText = "Do smth"
            };

            integralsSubCat.Add(taskInt1);
            LearningTask taskInt2 = new LearningTask
            {
                Name     = "Task 2",
                TaskText = "Do smth"
            };

            integralsSubCat.Add(taskInt2);
            rootCategory.Add(integralsSubCat);

            // Quadratic equations demo
            Category qeqSubCat = new Category();

            qeqSubCat.Name        = "Quadratic equations";
            qeqSubCat.Description = "Quadratic equations resolving";
            rootCategory.Add(qeqSubCat);

            // Derivatives demo
            Category derivativesSubCat = new Category();

            derivativesSubCat.Name        = "Derivatives";
            derivativesSubCat.Description = "Some exercises about derivatives";
            rootCategory.Add(derivativesSubCat);

            _readingCallback(rootCategory);
        }