public async Task <ObservableCollection <Course> > GetCourses(ServiceFilter filter)
        {
            filter.IsCourse = true;
            var ret = new ObservableCollection <Course>();

            foreach (var c in await Post <ServiceFilter, ObservableCollection <DtoService> >("GetServices", filter))
            {
                ret.Add(ServiceConverter.DtoToCourseViewModel(c));
            }
            return(ret);
        }
 public async Task <Course> GetCourse(int id)
 {
     return(ServiceConverter.DtoToCourseViewModel(await Post <int, DtoService>("GetService", id)));
 }