static isValidSpecifier(s) {
    return this.isValidZone(s);
  }
Returns whether the provided string is a valid specifier. This only checks the string's format, not that the specifier identifies a known zone; see isValidZone for that.
@param {string} s - The string to check validity on
@example IANAZone.isValidSpecifier("America/New_York") //=> true
@example IANAZone.isValidSpecifier("Sport~~blorp") //=> false
@deprecated For backward compatibility, this forwards to isValidZone, better use `isValidZone()` directly instead.
@return {boolean}