private static void FillIndex <TIndexKey>(IIndex <TIndexKey, int> index, [NotNull] FastCollection <TRaw> fastCollection, [NotNull] Func <TRaw, TIndexKey> selector)
{
var indexData = new List <IndexItem <TIndexKey, int> >();
foreach (var item in fastCollection.Items)
{
indexData.Add(new IndexItem <TIndexKey, int>(selector(item.Data), item.Id));
}
index.FillIndex(indexData);
}