docs: public static Pair<Integer, Integer> getPartitionReplicaTuple(String fileName) {
          if(!isFormatCorrect(fileName, ReadOnlyStorageFormat.READONLY_V2)) {
              throw new VoldemortException("Filename " + fileName
                                           + " does not comply with the format for storage format "
                                           + ReadOnlyStorageFormat.READONLY_V2);
          }
          int firstUnderScore = fileName.indexOf('_');
          int secondUnderScore = fileName.indexOf('_', firstUnderScore + 1);
  
          return Pair.create(Integer.parseInt(fileName.substring(0, firstUnderScore)),
                             Integer.parseInt(fileName.substring(firstUnderScore + 1,
                                                                 secondUnderScore)));
  
      }