sS translateUsingWordTree(S input, Map<S, O> tree) {  
  L<S> tok = javaTok(input);
  for (int i = 1; i < l(tok); i += 2)
    translateUsingWordTree_scanFrom(tok, i, tree);
  ret join(tok);
}
      
svoid translateUsingWordTree_scanFrom(L<S> tok, int i, Map<S, O> tree) {
  int j = i;
  Pair<S, Int> bestSolution = null; // replacement, index
  
  while true {
    S def = cast tree.get("<default>");
    if (def != null) {
      bestSolution = pair(def, j);
      print("best solution: " + sfu(bestSolution));
    }
   
    if (j >= l(tok)) break;
    
    O t = tree.get(tok.get(j));
    print(j + " / " + tok.get(j) + " => " + sfu(t));
    if (t == null) break;
    if (t instanceof S) {
      replaceTokens(tok, i, j+1, (S) t);
      ret;
    }
    tree = (Map) t;
    j += 2;
  }
  
  if (bestSolution != null)
    replaceTokens(tok, i, bestSolution.b-1, bestSolution.a);
}