code: def with_subject(self, subject):
          
          return self.__class__(
              self._signer,
              service_account_email=self._service_account_email,
              scopes=self._scopes,
              token_uri=self._token_uri,
              subject=subject,
              project_id=self._project_id,
              additional_claims=self._additional_claims.copy())
docs: Create a copy of these credentials with the specified subject.
  
          Args:
              subject (str): The subject claim.
  
          Returns:
              google.auth.service_account.Credentials: A new credentials
                  instance.