code: def exists(self):
          
          if '_id' not in self or self['_id'] is None:
              return False
  
          resp = self.r_session.head(self.document_url)
          if resp.status_code not in [200, 404]:
              resp.raise_for_status()
  
          return resp.status_code == 200
docs: Retrieves whether the document exists in the remote database or not.
  
          :returns: True if the document exists in the remote database,
              otherwise False