code: def add_filename_pattern(self, dir_name, pattern):
          
          full_pattern = '{}{}{}'.format(dir_name, os.sep, pattern)
          filename_regex = fnmatch.translate(full_pattern)
          self.regex_list.append(re.compile(filename_regex))
docs: Adds a Unix shell-style wildcard pattern underneath the specified directory
          :param dir_name: str: directory that contains the pattern
          :param pattern: str: Unix shell-style wildcard pattern