let
  aString = "a";

  bString = "b";
in
{
  hasAttrs = { a.b = null; } ? "${aString}".b;

  selectAttrs = { a.b = true; }.a."${bString}";

  selectOrAttrs = { }."${aString}" or true;

  binds = { "${aString}"."${bString}c" = true; }.a.bc;

  recBinds =
    rec {
      "${bString}" = a;
      a = true;
    }
    .b;

  multiAttrs =
    {
      "${aString}" = true;
      "${bString}" = false;
    }
    .a;
}
