sclass StringHead {
  replace InputStream with Reader.
  replace OutputStream with Writer.
  replace inputStream with reader.
  replace outputStream with writer.
  
  settable bool readMode;
  settable bool writeMode;
  gettable InputStream inputStream;
  gettable OutputStream outputStream;

  *() {}
  *(InputStream inputStream) { inputStream(inputStream); }
  *(OutputStream outputStream) { outputStream(outputStream); }
  
  selfType inputStream(InputStream inputStream) { this.inputStream = inputStream; readMode(true); this; }
  selfType outputStream(OutputStream outputStream) { this.outputStream = outputStream; writeMode(true); this; }
  
  void finish {}
  
  
}