static isValidZone(zone) {
    if (!zone) {
      return false;
    }
    try {
      new Intl.DateTimeFormat("en-US", { timeZone: zone }).format();
      return true;
    } catch (e) {
      return false;
    }
  }
Returns whether the provided string identifies a real zone
@param {string} zone - The string to check
@example IANAZone.isValidZone("America/New_York") //=> true
@example IANAZone.isValidZone("Fantasia/Castle") //=> false
@example IANAZone.isValidZone("Sport~~blorp") //=> false
@return {boolean}