code: public static void initializeIndex(String indexDir, String dataDir) {
          File indexDir_f = new File(indexDir);
          File dataDir_f = new File(dataDir);
  
          long start = new Date().getTime();
          try {
              int numIndexed = index(indexDir_f, dataDir_f);
              long end = new Date().getTime();
  
              System.err.println("Indexing " + numIndexed + " files took " + (end -start) + " milliseconds");
          } catch (IOException e) {
              System.err.println("Unable to index "+indexDir_f+": "+e.getMessage());
          }
      }
docs: Initializes an index given the index directory and data directory.
  
  @param indexDir a {@code String} containing the directory where the index
  will be stored
  @param dataDir a {@code String} containing the directory where the data
  is found