// e.g. "* is *" to "<1> to <2>"
sS starsToAngleBracketedNumbers(S s) {
  LS tok = javaTokWithAngleBrackets(s);
  int count = 0;
  for (int idx : indicesOf(tok, "*"))
    tok.set(idx, angleBracketed(str(++count)));
  ret join(tok);
}