public IEnumerable <T> ForTest01 <T>(IEnumerable <T> source, Action <T, int> action) { IEnumerable <T> result = EnumerableExtension.For <T>(source, action); return(result); // TODO: add assertions to method EnumerableExtensionTest.ForTest01(IEnumerable`1<!!0>, Action`2<!!0,Int32>) }