code: def url(self):
          
          base_url = "https://lists.fedoraproject.org/archives"
          archived_at = self._get_archived_at()
          if archived_at and archived_at.startswith("<"):
              archived_at = archived_at[1:]
          if archived_at and archived_at.endswith(">"):
              archived_at = archived_at[:-1]
          if archived_at and archived_at.startswith("http"):
              return archived_at
          elif archived_at:
              return base_url + archived_at
          else:
              return None
docs: An URL to the email in HyperKitty
  
          Returns:
              str or None: A relevant URL.