public static IEnumerable <TResult> Select <TSource, TResult>(IEnumerable <TSource> source, Func <TSource, int, TResult> selector)
{
if (source == null)
{
throw ThrowHelper.ArgumentNull("source");
}
if (selector == null)
{
throw ThrowHelper.ArgumentNull("selector");
}
return(Enumerable.SelectIterator <TSource, TResult>(source, selector));
}