Could you name the two expressions, for easier reference later on? Something like:

```augeas
let comment_gen (space:regexp) (sto:regexp) =
          [ label "#comment" . del ("#" . space) "# " . store sto . eol ]

let comment =
     let comment_withsign = comment_gen Rx.space /([!+-].*[^ \t\n]|[!+-])/
  in let_comment_nosign = comment_gen Rx.opt_space /([^ \t\n+!-].*[^ \t\n]|[^ \t\n+!-])
  in comment_withsign | comment_nosign
```