code: public static synchronized 
    Statistics getStatistics(String scheme, Class<? extends FileSystem> cls) {
      Statistics result = statisticsTable.get(cls);
      if (result == null) {
        result = new Statistics(scheme);
        statisticsTable.put(cls, result);
      }
      return result;
    }
docs: Get the statistics for a particular file system
  @param cls the class to lookup
  @return a statistics object