static Map<S, T3<S>> ai_parseTriple_cache = synchronizedMRUCache(1000);

static T3<S> ai_parseTriple(S s) {
  L<S> l = map tok_unCurlyBracket(splitAtSimpleArrow(tok_combineCurlyBrackets_keep(javaTok(s))));
  if (l(l) == 2) l.add(".");
  ret listToTriple(l);
}