setDataResidency(region) {
    if (!REGION_HOST_MAP.hasOwnProperty(region)) {
      console.warn('Region can only be "global" or "eu".');
    } else {
      this.sendgrid_region = region;
      this.setDefaultRequest('baseUrl', REGION_HOST_MAP[region]);
    }
    return this;
  }
Global is the default residency (or region)
Global region means the message will be sent through https://api.sendgrid.com
EU region means the message will be sent through https://api.eu.sendgrid.com