private static LinqBatchItem <TResult> For <TSource, TResult>(IQueryable <TSource> query, Expression <Func <IQueryable <TSource>, TResult> > selector)
 {
     return(LinqBatchItem.Create(query, selector));
 }
 private static LinqBatchItem <TResult> For <TResult>(IQueryable <TResult> query)
 {
     return(LinqBatchItem.Create(query));
 }