Pass lambda into template

[Andrey via Digitalmars-d-learn]

Hello,

Here is a code with comments: https://run.dlang.io/is/BNl2Up.

I don't understand how to pass lambda into template.
I get an error:

onlineapp.d(18): Error: template instance `qwerty!((i) => "arg" ~ i.to!string ~ "[0] == '?'", "||")` cannot use local __lambda1 as parameter to non-global template qwerty(alias mapper, alias delimiter)