Pass lambda into template

[Andrey]

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)