What does auto std.stdio.File.ByChunkImpl byChunk (ulong chunkSize ); mean?

[kdevel]

On Friday, 3 August 2018 at 17:06:16 UTC, Adam D. Ruppe wrote:
> On Friday, 3 August 2018 at 16:58:26 UTC, kdevel wrote:
>> What does
>>
>>   auto std.stdio.File.ByChunkImpl byChunk (
>>      ulong chunkSize
>>   );
>>
>> on https://dlang.org/library/std/stdio/file.by_chunk.html mean?
>
>
> It looks like ddox trying to tell you what the auto actually is.

But that indented "code" is not syntactically valid D. Isn't it?