public DiskBrowserViewModel(IDiskService diskService, UserDto user)
{
if (diskService == null) throw new ArgumentNullException("diskService");
if (user == null) throw new ArgumentNullException("user");
_disks = new ObservableCollection<DiskDto>(diskService.Disks(user));
SelectItemCommand = new Command(SelectItem, o => SelectedDisk != null);
}