code: def _retrieve_info(self, request):
          
          info = _metadata.get_service_account_info(
              request,
              service_account=self._service_account_email)
  
          self._service_account_email = info['email']
          self._scopes = info['scopes']
docs: Retrieve information about the service account.
  
          Updates the scopes and retrieves the full service account email.
  
          Args:
              request (google.auth.transport.Request): The object used to make
                  HTTP requests.