Generated by SassMeister.com.

input.scss

@function thing($str) {
    @return $str;
}

@at-root {
    .a {
        top: thing(cap(8));
    }
}

output.css

.a {
  top: cap(8);
}

settings.json

{
  "sass": {
    "compiler": "dart-sass/1.26.11",
    "extensions": {},
    "syntax": "SCSS",
    "outputStyle": "expanded"
  },
  "autoprefixer": false
}