!752

sclass Vessel {

  new L<S> data;

  int index;

  *() {}

  *(L<S> *data, int *index) {}

  void add(S s) {

    data.add(simplify(s));

  }

  bool consume(S s) {

    if (end()) ret false;

    s = simplify(s);

    /*if (same(next(), s)) {

      ++index;

      ret true;

    }

    ret false;*/

    //++index;

    if (!same(next(), s)) {

      --index;

      ret false;

    }

    ret true;

  }

  void restart() {

    index = 0;

  }

  // may be null if index after end

  S next() {

    ret end() ? null : get(data, index++);

  }

  bool end() {

    ret index >= l(data);

  }

  public Vessel clone() {

    ret new Vessel(cloneList(data), index);

  }

}

static S simplify(S s) {

  ret s.trim().toUpperCase();

}

static bool same(S a, S b) {

  ret eq(a, b);

}

static new L<Vessel> vessels;

p {

  new Vessel v;

  v.add("There is RAIN");

  v.add("I need a COAT");

  vessels.add(v);

}

synchronized answer {

  if (!tb()) null;

  for (Vessel v : vessels) {

    if (v.consume(s)) {

      S answer = v.next();

      v.restart();

      if (nempty(answer))

        ret answer;

    }

  }

}