code: def _get_file_list(self, working_dir, file_regex=re.compile(r'.*'), ftp=None):
          
  
          if ftp is None:
              ftp = ftplib.FTP(BGEE_FTP)
              ftp.login("anonymous", "info@monarchinitiative.org")
  
          working_dir = "{}{}".format(self.version, working_dir)
          LOG.info('Looking for remote files in %s', working_dir)
  
          ftp.cwd(working_dir)
          remote_files = ftp.nlst()
  
          # LOG.info('All remote files \n%s', '\n'.join(remote_files))
          files_to_download = [
              dnload for dnload in remote_files if re.match(file_regex, dnload) and
              re.findall(r'^\d+', dnload)[0] in self.tax_ids]
          # LOG.info('Choosing remote files \n%s', '\n'.join(list(files_to_download)))
  
          return files_to_download, ftp
docs: Get file list from ftp server filtered by taxon
          :return: Tuple of (Generator object with Tuple(
              file name, info object), ftp object)