docs: def text_opener(path, pattern='', verbose=False):
      """Opener that opens single text file.
  
      :param str path: Path.
      :param str pattern: Regular expression pattern.
      :return: Filehandle(s).
      """
      source = path if is_url(path) else os.path.abspath(path)
      filename = os.path.basename(path)
  
      if pattern and not re.match(pattern, filename):
          logger.verbose('Skipping file: {}, did not match regex pattern "{}"'.format(os.path.abspath(path), pattern))
          return
  
      filehandle = urlopen(path) if is_url(path) else open(path)
      logger.verbose('Processing file: {}'.format(source))
      yield filehandle