static <A> void linkVarsVerbose(IVarWithNotify<A> var1, IVarWithNotify<A> var2) {
  if (var1 == null || var2 == null) ret;
  var2.onChange(value -> {
    print("linkVars: Setting var1 to " + value);
    var1.set(value);
  });
  var1.onChangeAndNow(value -> {
    print("linkVars: Setting var2 to " + value);
    var2.set(value);
  });
}

Began life as a copy of #1034554