public ViewModel Create(string name)
 {
     var type = _assembly.GetType(name);
     var instance = Activator.CreateInstance(type);
     var vm = new ViewModel(instance);
     _viewModels[vm.GetHashCode().ToString()] = vm;
     return vm;
 }
 public void Add(ViewModel vm)
 {
     _viewModels[vm.GetHashCode().ToString()] = vm;
 }