code: private Path renameToInProgressFile(Path file)
            throws IOException {
      Path newFile =  new Path( file.toString() + inprogress_suffix );
      try {
        if (hdfs.rename(file, newFile)) {
          return newFile;
        }
        throw new RenameException(file, newFile);
      } catch (IOException e){
        throw new RenameException(file, newFile, e);
      }
    }
docs: Renames files with .inprogress suffix
  @return path of renamed file
  @throws if operation fails