def set_version(self, version):
        """
        Set the version subfield (RFC 2459, section 4.1.2.1) of the certificate
        request.

        :param int version: The version number.
        :return: ``None``
        """
        set_result = _lib.X509_REQ_set_version(self._req, version)
        _openssl_assert(set_result == 1)
Set the version subfield (RFC 2459, section 4.1.2.1) of the certificate
        request.

        :param int version: The version number.
        :return: ``None``