static <A> S joinWithComma(Collection<A> c) {
  ret join(", ", c);
}

sS joinWithComma(O... c) {
  ret join(", ", c);
}

sS joinWithComma(S... c) {
  ret join(", ", c);
}

ifclass Pair
sS joinWithComma(Pair p) {
  ret p == null ? "" : joinWithComma(str(p.a), str(p.b));
}
endif