code: public FSDataOutputStream append(Path f, int bufferSize,
        Progressable progress) throws IOException {
      if (!exists(f)) {
        throw new FileNotFoundException("File " + f + " not found.");
      }
      if (getFileStatus(f).isDir()) {
        throw new IOException("Cannot append to a diretory (=" + f + " ).");
      }
      return new FSDataOutputStream(new LocalFSFileOutputStream(f, true),
                                    statistics);
    }
docs: {@inheritDoc}