class Zoom implements Modem {

  /**
   * Accepts all visitors but honors only ZoomVisitor.
   */
  @Override
  public void accept(ModemVisitor modemVisitor) {<FILL_FUNCTION_BODY>}

  /**
   * Zoom modem's toString method.
   */
  @Override
  public String toString() {
    return "Zoom modem";
  }
}

    if (modemVisitor instanceof ZoomVisitor) {
      ((ZoomVisitor) modemVisitor).visit(this);
    } else {
      LOGGER.info("Only ZoomVisitor is allowed to visit Zoom modem");
    }
  
<no_super_class>