docs: def iter_paragraph(filename, filetype):
      """
      A helper function to iterate through the diff types of Wikipedia data inputs.
      :param arguments: The docopt arguments
      :type arguments: dict
      :return: A generator yielding a pargraph of text for each iteration.
      """
      assert filetype in ['jsonzip', 'jsondir', 'wikidump']
  
      # Iterating through paragraphes from the Anntoated Wikipedia zipfile.
      if filetype == 'jsonzip':
          with ZipFile(filename, 'r') as zip_in:
              # Iterate through the individual files.
              for infile in zip_in.namelist():
                  if infile.endswith('/'): # Skip the directories.
                      continue
                  print(infile, end='\n', file=sys.stderr) # Logging progress.
                  with zip_in.open(infile) as f_in:
                      for line in io.TextIOWrapper(f_in, 'utf8'):
                          # Each line is a separate json.
                          data = json.loads(line)
                          # The useful text under 'text' key.
                          yield data['text'].strip()
  
      # Iterating through paragraphes from the Anntoated Wikipedia directory.
      elif filetype == 'jsondir':
          for root, dirs, files in os.walk(filename):
              for wiki_file in files:
                  infile = os.path.join(root, wiki_file)
                  print(infile, end='\n', file=sys.stderr) # Logging progress.
                  with io.open(infile, 'r', encoding='utf8') as f_in:
                      for line in f_in:
                          # Each line is a separate json.
                          data = json.loads(line)
                          # The useful text under 'text' key.
                          yield data['text'].strip()
  
      # Iterating through paragraphes from the Wikipedia dump.
      elif filetype == 'wikidump':
          # Simply iterate through every line in the dump
          # and treat each line as a paragraph.
          with io.open(filename, 'r', encoding='utf8') as f_in:
              for line_count, paragraph in enumerate(f_in):
                  if line_count % 100000:
                      _msg = 'Processing line {}\n'.format(line_count)
                      print(_msg, file=sys.stderr) # Logging progress.
                  if pargraph:
                      yield paragraph