code: private void printErrors(final List<String> filteredDoc,
        final List<String> filteredRefs, final List<String> filteredPreds) {
      this.printStream.println("Errors: {");
      this.printStream.println("Tok: Ref | Pred");
      this.printStream.println("---------------");
      for (int i = 0; i < filteredDoc.size(); i++) {
        this.printStream.println(filteredDoc.get(i) + ": " + filteredRefs.get(i)
            + " | " + filteredPreds.get(i));
      }
      this.printStream.println("}\n");
    }
docs: Auxiliary method to print tag errors
  
  @param filteredDoc
  the document tokens which were tagged wrong
  @param filteredRefs
  the reference tags
  @param filteredPreds
  the predicted tags