CT-String as a Symbol

["Nordlöw" via Digitalmars-d-learn]

At

https://github.com/nordlow/justd/blob/master/typecons_ex.d#L143

I can't figure out how to make the call to

     mixin genOps!I;

expand to, for instance,

     mixin genOps!Index

in the case when I = "Index".

Help please.