static <A extends Iterable> A pnl(A l) {
  printNumberedLines(l);
  ret l;
}

static void pnl(Map map) {
  printNumberedLines(map);
}

static void pnl(O[] a) {
  printNumberedLines(a);
}

static void pnl(S s) {
  printNumberedLines(lines(s));
}