code: def list_folder(cls, session, mailbox, folder):
          
          return cls(
              '/mailboxes/%d/folders/%s/conversations.json' % (
                  mailbox.id, folder.id,
              ),
              session=session,
          )
docs: Return conversations in a specific folder of a mailbox.
  
          Args:
              session (requests.sessions.Session): Authenticated session.
              mailbox (helpscout.models.Mailbox): Mailbox that folder is in.
              folder (helpscout.models.Folder): Folder to list.
  
          Returns:
              RequestPaginator(output_type=helpscout.models.Conversation):
                  Conversations iterator.