async function getRefreshToken() {
  logger.debug('Loading Tuya refresh token...');
  const refreshToken = await this.gladys.variable.getValue(GLADYS_VARIABLES.REFRESH_TOKEN, this.serviceId);
  logger.debug('Tuya refresh token well loaded');
  return refreshToken;
}
@description Implements Tuya connector get refresh token method.
@returns {Promise} Tuya refresh token.
@example
await tuya.getRefreshToken();
@see https://github.com/tuya/tuya-connector-nodejs#custom-tokenstore