public static ValueEnumerableExtensions.WhereAtEnumerable <ValueWrapper <TSource>, ValueWrapper <TSource> .Enumerator, TSource, TPredicate> WhereAt <TSource, TPredicate>( this ImmutableStack <TSource> source, TPredicate predicate) where TPredicate : struct, IFunction <TSource, int, bool> => ValueEnumerableExtensions.WhereAt <ValueWrapper <TSource>, ValueWrapper <TSource> .Enumerator, TSource, TPredicate>(new ValueWrapper <TSource>(source), predicate);