def get_templatetag_module(cls):
        """
        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
        """
        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]
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