mixin assembler does not work?

[Foo via Digitalmars-d-learn]

On Sunday, 20 July 2014 at 15:54:15 UTC, bearophile wrote:
>> mixin template Vala2(uint count, alias arr) {
>
> What about disallowing "mixin templatename" unless you add 
> "mixin" before the "template" keyword?
>
> Bye,
> bearophile

I do not understand?