static <A, B> LPair<A, B> lambdaMapLike printFunctionValues(S desc default shorten_str(f, 50), IF1<A, B> f, Iterable<A> l) {
  var l = mapToPairsB(f, l);
  print(mapPairsToLines(l, (in, out) -> desc + ": " + in + " -> " + out));
  ret l;
}