code: @Deprecated
      public static EchoOutput adapt(final Appendable appendable) {
          return new EchoOutput() {
              @Override
              public void onReceive(int input, String string) throws IOException {
                  appendable.append(string);
              }
  
              @Override
              public void onSend(String string) throws IOException {
                  appendable.append(string);
              }
          };
      }
docs: Creates an instance of {@link EchoOutput} which appends all the input and output data to
  the given appender.
  
  @param appendable the delegate
  @return the instance