Add docstring

core/managers.py

@@ -1,5 +1,6 @@
 import structlog
 
+from django.core.cache import caches
 from django.db import models
 
 logger = structlog.get_logger()
@@ -7,7 +8,8 @@ logger = structlog.get_logger()
 
 class RenderedContentManager(models.Manager):
     def delete_by_content_type(self, content_type):
+        """Deletes all rendered content of a given type."""
         self.filter(content_type=content_type).delete()
         logger.info(
             "rendered_content_manager_delete_by_content_type", content_type=content_type
-        )
+        )