static Set<ES> applyWordTokRules_es(L<WordTokRule> rules, ES s) {
  ret concatListsToCISet_es(map(rules, rule ->
    rule.matches(s!) ? getStringEmits_es(rule) : null
  ));
}

static Set<ES> applyWordTokRules_es(L<WordTokRule> rules, Collection<ES> inputs) {
  Set<ES> out = cloneLinkedCISet_es(inputs);
  for unnull (ES input : inputs)
    functionReturningList_transitiveHull_ciSet_es(func(ES s) -> Collection<ES> { applyWordTokRules_es(rules, s) }, input, seen := out);
  ret out;
}

Began life as a copy of #1023191