[System.Runtime.CompilerServices.AsyncStateMachine(C1.CollectionView.ICollectionViewEx/d__19`1)] 
[System.Runtime.CompilerServices.Extension()] 
public static System.Threading.Tasks.Task FilterAsync<T>( 
   ICollectionView<T> collectionView, 
   System.Func<object,bool> predicate 
) 
where T: class