<===> input.scss
h1 { color: blue; } 
@warn "Don't crash the ambulance, whatever you do"

<===> output.css
h1 {
  color: blue;
}

<===> warning
WARNING: Don't crash the ambulance, whatever you do
         on line 2 of input.scss

<===> warning-dart-sass
WARNING: Don't crash the ambulance, whatever you do
    input.scss 2:1  root stylesheet