It's not my code :) However, tagged template literals won't allow dict expansion the way this solution does. Also, a template literal is evaluated at the time of assignment. This will allow you to re-use an arbitrary template string with any matching values:

  tpl = applyTemplate("Hello ${a}");
  tpl({"a": "you"}); // --> Hello you
  tpl({"a": "dude"});  // --> Hello dude