How to use the bless.config.bless_config.REMOTE_USERNAMES_BLACKLIST_OPTION function in bless

def test_validate_multiple_principals(test_input):
    BlessSchema().validate_remote_usernames(test_input)

    schema = BlessSchema()
    schema.context[USERNAME_VALIDATION_OPTION] = USERNAME_VALIDATION_OPTIONS.principal.name
    schema.context[REMOTE_USERNAMES_VALIDATION_OPTION] = USERNAME_VALIDATION_OPTIONS.principal.name
    schema.context[REMOTE_USERNAMES_BLACKLIST_OPTION] = 'balrog'
    schema.validate_remote_usernames(test_input)

def validate_remote_usernames(self, remote_usernames):
        if REMOTE_USERNAMES_VALIDATION_OPTION in self.context:
            username_validation = USERNAME_VALIDATION_OPTIONS[self.context[REMOTE_USERNAMES_VALIDATION_OPTION]]
        else:
            username_validation = USERNAME_VALIDATION_OPTIONS[REMOTE_USERNAMES_VALIDATION_DEFAULT]
        if REMOTE_USERNAMES_BLACKLIST_OPTION in self.context:
            username_blacklist = self.context[REMOTE_USERNAMES_BLACKLIST_OPTION]
        else:
            username_blacklist = REMOTE_USERNAMES_BLACKLIST_DEFAULT
        for remote_username in remote_usernames.split(','):
            validate_user(remote_username, username_validation, username_blacklist)

certificate_validity_before_seconds = config.getint(BLESS_OPTIONS_SECTION,
                                                        CERTIFICATE_VALIDITY_BEFORE_SEC_OPTION)
    certificate_validity_after_seconds = config.getint(BLESS_OPTIONS_SECTION,
                                                       CERTIFICATE_VALIDITY_AFTER_SEC_OPTION)
    entropy_minimum_bits = config.getint(BLESS_OPTIONS_SECTION, ENTROPY_MINIMUM_BITS_OPTION)
    random_seed_bytes = config.getint(BLESS_OPTIONS_SECTION, RANDOM_SEED_BYTES_OPTION)
    ca_private_key = config.getprivatekey()
    certificate_extensions = config.get(BLESS_OPTIONS_SECTION, CERTIFICATE_EXTENSIONS_OPTION)

    # Process cert request
    schema = BlessSchema(strict=True)
    schema.context[USERNAME_VALIDATION_OPTION] = config.get(BLESS_OPTIONS_SECTION, USERNAME_VALIDATION_OPTION)
    schema.context[REMOTE_USERNAMES_VALIDATION_OPTION] = config.get(BLESS_OPTIONS_SECTION,
                                                                    REMOTE_USERNAMES_VALIDATION_OPTION)
    schema.context[REMOTE_USERNAMES_BLACKLIST_OPTION] = config.get(BLESS_OPTIONS_SECTION,
                                                                   REMOTE_USERNAMES_BLACKLIST_OPTION)

    try:
        request = schema.load(event).data
    except ValidationError as e:
        return error_response('InputValidationError', str(e))

    logger.info('Bless lambda invoked by [user: {0}, bastion_ips:{1}, public_key: {2}, kmsauth_token:{3}]'.format(
        request.bastion_user,
        request.bastion_user_ip,
        request.public_key_to_sign,
        request.kmsauth_token))

    # Make sure we have the ca private key password
    if bless_cache.ca_private_key_password is None:
        return error_response('ClientError', bless_cache.ca_private_key_password_error)
    else:

certificate_validity_before_seconds = config.getint(BLESS_OPTIONS_SECTION,
                                                        CERTIFICATE_VALIDITY_BEFORE_SEC_OPTION)
    certificate_validity_after_seconds = config.getint(BLESS_OPTIONS_SECTION,
                                                       CERTIFICATE_VALIDITY_AFTER_SEC_OPTION)
    entropy_minimum_bits = config.getint(BLESS_OPTIONS_SECTION, ENTROPY_MINIMUM_BITS_OPTION)
    random_seed_bytes = config.getint(BLESS_OPTIONS_SECTION, RANDOM_SEED_BYTES_OPTION)
    ca_private_key = config.getprivatekey()
    certificate_extensions = config.get(BLESS_OPTIONS_SECTION, CERTIFICATE_EXTENSIONS_OPTION)

    # Process cert request
    schema = BlessSchema(strict=True)
    schema.context[USERNAME_VALIDATION_OPTION] = config.get(BLESS_OPTIONS_SECTION, USERNAME_VALIDATION_OPTION)
    schema.context[REMOTE_USERNAMES_VALIDATION_OPTION] = config.get(BLESS_OPTIONS_SECTION,
                                                                    REMOTE_USERNAMES_VALIDATION_OPTION)
    schema.context[REMOTE_USERNAMES_BLACKLIST_OPTION] = config.get(BLESS_OPTIONS_SECTION,
                                                                   REMOTE_USERNAMES_BLACKLIST_OPTION)

    try:
        request = schema.load(event).data
    except ValidationError as e:
        return error_response('InputValidationError', str(e))

    logger.info('Bless lambda invoked by [user: {0}, bastion_ips:{1}, public_key: {2}, kmsauth_token:{3}]'.format(
        request.bastion_user,
        request.bastion_user_ip,
        request.public_key_to_sign,
        request.kmsauth_token))

    # Make sure we have the ca private key password
    if bless_cache.ca_private_key_password is None:
        return error_response('ClientError', bless_cache.ca_private_key_password_error)