internal static MemorySelectRefEnumerable <TSource, TResult, FunctionInWrapper <TSource, TResult> > Select <TSource, TResult>(this ReadOnlyMemory <TSource> source, FunctionIn <TSource, TResult> selector)
 => source.SelectRef <TSource, TResult, FunctionInWrapper <TSource, TResult> >(new FunctionInWrapper <TSource, TResult>(selector));