code: def get_templatetag_module(cls):
          
          if cls not in CacheTag._templatetags_modules:
              # find the library including the main templatetag of the current class
              all_tags = cls.get_all_tags_and_filters_by_function()['tags']
              CacheTag._templatetags_modules[cls] = all_tags[CacheTag._templatetags[cls]['cache']][0]
          return CacheTag._templatetags_modules[cls]
docs: Return the templatetags module name for which the current class is used.
          It's used to render the nocache blocks by loading the correct module