code: def iter_format_modules(lang):
      
      if check_for_language(lang):
          format_locations = []
          for path in CUSTOM_FORMAT_MODULE_PATHS:
              format_locations.append(path + '.%s')
          format_locations.append('django.conf.locale.%s')
          locale = to_locale(lang)
          locales = [locale]
          if '_' in locale:
              locales.append(locale.split('_')[0])
          for location in format_locations:
              for loc in locales:
                  try:
                      yield import_module('.formats', location % loc)
                  except ImportError:
                      pass
docs: Does the heavy lifting of finding format modules.