<===> input.scss
$ls: ((foo,));

foo {
  baz: length($ls);
  baz: type-of($ls);
  baz: inspect($ls);
}

bar {
  baz: length(&);
  baz: type-of(&);
  baz: inspect(&);
}

foo {
  string: inspect(&);
  str-length: str-length(inspect(&));
  list-length: length(&);
}

foo, bar {
  string: inspect(&);
  str-length: str-length(inspect(&));
  list-length: length(&);
}

<===> output.css
foo {
  baz: 1;
  baz: list;
  baz: (foo,);
}

bar {
  baz: 1;
  baz: list;
  baz: (bar,);
}

foo {
  string: (foo,);
  str-length: 6;
  list-length: 1;
}

foo, bar {
  string: foo, bar;
  str-length: 8;
  list-length: 2;
}