docs: def prepare_xml(args, parser):
      """Prepares XML files for stripping.
  
      This process creates a single, normalised TEI XML file for each
      work.
  
      """
      if args.source == constants.TEI_SOURCE_CBETA_GITHUB:
          corpus_class = tacl.TEICorpusCBETAGitHub
      else:
          raise Exception('Unsupported TEI source option provided')
      corpus = corpus_class(args.input, args.output)
      corpus.tidy()