code: @Beta
    public static Writer asWriter(Appendable target) {
      if (target instanceof Writer) {
        return (Writer) target;
      }
      return new AppendableWriter(target);
    }
docs: Returns a Writer that sends all output to the given {@link Appendable} target. Closing the
  writer will close the target if it is {@link Closeable}, and flushing the writer will flush the
  target if it is {@link java.io.Flushable}.
  
  @param target the object to which output will be sent
  @return a new Writer object, unless target is a Writer, in which case the target is returned