scope mechList_opt_tlft_cached.

static Map<S, MechListDependentCache<LS>> #cache = ciMap();
static Lock #lock = lock();

static LS mechList_opt_tlft_cached(S name) {
  MechListDependentCache<LS> listCache;
  {
    lock lock;
    listCache = cache.get(name);
    if (listCache == null)
       cache.put(name, listCache
        = MechListDependentCache(name, f<S, LS> tlft));
  }
  ret listCache!;
}

end scope

Began life as a copy of #1014312