sclass StringHead {
  settable bool readMode;
  settable bool writeMode;
  gettable InputStream inputStream;
  gettable OutputStream outputStream;

  *() {}
  *(Reader reader) { reader(reader); }
  *(Writer writer) { writer(writer); }
  
  selfType reader(Reader reader) { this.reader = reader; readMode(true); this; }
  selfType writer(Writer writer) { this.writer = writer; writeMode(true); this; }
  
  void finish {}
  
  
}