docs: def delete_attachment(cls, session, attachment):
          """Delete an attachment.
  
          Args:
              session (requests.sessions.Session): Authenticated session.
              attachment (helpscout.models.Attachment): The attachment to
                  be deleted.
  
          Returns:
              NoneType: Nothing.
          """
          return super(Conversations, cls).delete(
              session,
              attachment,
              endpoint_override='/attachments/%s.json' % attachment.id,
              out_type=Attachment,
          )