code: function timegm(timegmt) {
        var year   = timegmt[0];
        var month  = timegmt[1];
        var day    = timegmt[2];
        var hour   = timegmt[3];
        var minute = timegmt[4];
        var second = timegmt[5];
  
        if(month < 1 || month > 12) {
          throw new IllegalMonthError();
        }
  
        if(day < 1 || day > (_DAYS_IN_MONTH[month] + (month === 2 && isleap(year)))) {
          throw new IllegalDayError();
        }
  
        if(hour < 0 || hour > 23 || minute < 0 || minute > 59 || second < 0 || second > 59) {
          throw new IllegalTimeError();
        }
  
        var days = _toordinal(year, month, 1) - 719163 + day - 1;
        var hours = (days * 24) + hour;
        var minutes = (hours * 60) + minute;
        var seconds = (minutes * 60) + second;
  
        return seconds;
      }
docs: Unrelated but handy function to calculate Unix timestamp from GMT.
  
  @param {Array} tuple
  @throws {IllegalMonthError} If the provided month element is invalid.
  @throws {IllegalDayError} If the provided day element is invalid.
  @api public