static final class Symbol {
  S text;
  Symbol master;
  
  *() {}
  *(S *text, bool dummy) {} // weird signature to prevent accidental calling
  
  bool isMaster() { ret master == this; }
  public int hashCode() { ret main.hashCode(master.text); }
  toString { ret text; }
  public bool equals(O o) {
    ret o instanceof Symbol && master == o/Symbol.master;
  }
}