Docs for `Group` type

[ag0aep6g via Digitalmars-d-learn]

On 07/12/2016 01:40 PM, Bahman Movaqar wrote:
> Yes.  I'm working on Stockman[1] a playground to learn D.
> In file `etl.d`, line 110 [2], if I change the line to
>      auto refInvoice = group[1].takeOne();
> the file will not compile.  I have attached the compile error to this
> message.

Do you also add the import of takeOne? takeOne is not a range primitive, 
but a function that works on ranges. Need to import it in order to use it.