// params = pair(inputs), output, pair(inputs), output, ...
svoid mapLike testFunctionValues_twoArgs(O function, O... params) {
  for (int i = 0; i+1 < l(params); i += 2) {
    Pair in = cast params[i];
    O expected = params[i+1];
    print(function + "(" + in + ")");
    assertEqualsVerbose(expected, callFWithVarArgs(function, in.a, in.b));
  }
}