code: def get_all_identifiers(dataset):
      
      for document in tqdm(
              dataset.glob("**/*.xhtml.zip"), desc="get_all_identifiers(%s)" % dataset.name):
          identifier = get_identifier(document)
          directory = document.parents[0]
          yield (directory, identifier)
docs: Extracts paragraph identifiers from a dataset in the NTCIR-11 Math-2, and NTCIR-12 MathIR XHTML5
      format.
  
      Parameters
      ----------
      dataset : Path
          A path to a dataset.
  
      Yields
      -------
      (Path, str)
          A parent directory of a paragraph, and the identifier of the paragraph.