code: def files_before(self, *, bundle: str=None, tags: List[str]=None, before:
                       str=None) -> models.File:
          
          query = self.files(tags=tags, bundle=bundle)
          if before:
              before_dt = parse_date(before)
              query = query.join(models.Version).filter(models.Version.created_at < before_dt)
  
          return query
docs: Fetch files before date from store