private void UpdateSelectionTrigger(HospitalViewModel hospital)
 {
     if (hospital.IsSelected)
     {
         SelectedHospitals.Add(hospital);
     }
     else
     {
         SelectedHospitals.Remove(hospital);
     }
     RaisePropertyChanged(() => IsAllSelected);
     AssignCategoryCommand.RaiseCanExecuteChanged();
 }