// last element of inAndExpected is expected result
svoid mapLike testFunctionValue(O function, O... inAndExpected) {
  S strIn = str(in);
  S msg = function + "(" + strIn + ")";
  O expected = last(inAndExpected);
  print(msg);
  assertEqualsVerbose(strIn, expected, callF(function, dropLast(in));
}