arguments to the constructor, so you can
    specify additional scopes and a subject if necessary::

        credentials = (
            _service_account_async.IDTokenCredentials.from_service_account_file(
                'service-account.json',
                scopes=['email'],
                subject='user@example.com'))

    The credentials are considered immutable. If you want to modify the scopes
    or the subject used for delegation, use :meth:`with_scopes` or
    :meth:`with_subject`::

        scoped_credentials = credentials.with_scopes(['email'])
        delegated_credentials = credentials.with_subject(subject)

    c