std.algorithm can not be used inside pure functions?

[Szabo Bogdan via Digitalmars-d-learn]

On Saturday, 6 May 2017 at 13:21:10 UTC, Adam D. Ruppe wrote:
> On Saturday, 6 May 2017 at 13:19:17 UTC, Szabo Bogdan wrote:
>> a.begin.toISOExtString,
>
> I believe that function is not marked pure if it is a SysTime 
> because it needs to pull global timezone info.
>
> What is the type of a.begin?

oh yes, I get it... begin and end are `SysTime`.. there is any 
workaround for this?