code: def receive_update_post(self, post_params):
          
  
          if isinstance(post_params, dict):
              required_params = ['action', 'email', 'sig']
              if not self.check_for_valid_postback_actions(required_params, post_params):
                  return False
          else:
              return False
  
          if post_params['action'] != 'update':
              return False
  
          signature = post_params['sig']
          post_params = post_params.copy()
          del post_params['sig']
  
          if signature != get_signature_hash(post_params, self.secret):
              return False
  
          return True
docs: Update postbacks