Testing some singleton implementations

[Andrej Mitrovic]

On 1/31/14, Stanislav Blinov <stanislav.blinov at gmail.com> wrote:
> On Friday, 31 January 2014 at 11:08:42 UTC, Dejan Lekic wrote:
>
>> I believe it should have been "final" instead of "const".
>
> But D doesn't have "final" :) In any event, that article by Mike
> Parker is about D1.
>

AFAIK D1's final was equivalent to D2's immutable. But I maybe
remembering that wrong. Or maybe D2 initially used final before
settling for the new keyword immutable, to avoid confusion by users.