code: function tzset (tz) {
    if (tz) {
      process.env.TZ = tz;
    }
    var usedTz = process.env.TZ;
    var rtn = bindings.tzset();
    debug('set the current timezone to:', usedTz);
    if (!rtn.tzname[1] && rtn.timezone === 0) {
      debug('got bad zoneinfo object:', rtn);
      var err = new Error("Unknown Timezone: '" + usedTz + "'");
      for (var i in rtn) {
        err[i] = rtn[i];
      }
      throw err;
    }
    exports.currentTimezone = usedTz;
    exports._currentZoneinfo = rtn;
    return rtn;
  }
docs: The user-facing 'tzset' function is a thin wrapper around the native binding to
  'tzset()'. This function accepts a timezone String to set the process' timezone
  to. Returns an object with the zoneinfo for the timezone.
  
  Throws (on *some* platforms) when the desired timezone could not be loaded.
  
  Sets the `currentTimezone` property on the exports.