docs: def _generate_filenames(sources):
      """Generate filenames.
  
      :param tuple sources: Sequence of strings representing path to file(s).
      :return: Path to file(s).
      :rtype: :py:class:`str`
      """
      for source in sources:
          if os.path.isdir(source):
              for path, dirlist, filelist in os.walk(source):
                  for fname in filelist:
                      if GenericFilePath.is_compressed(fname):
                          if VERBOSE:
                              print("Skipping compressed file: {}".format(os.path.abspath(fname)))
                          continue
                      else:
                          yield os.path.join(path, fname)
  
          elif os.path.isfile(source):
              yield source
  
          elif source.isdigit():
              analysis_id = "AN{}".format(source.zfill(6))
              url = MWREST.format(analysis_id)
              yield url
  
          elif GenericFilePath.is_url(source):
              yield source
  
          else:
              raise TypeError("Unknown file source.")