private static LocalDateTime add(LocalDateTime t,int val,String unit){
  ChronoUnit uu=CALENDAR_UNITS.get(unit);
  if (null == uu) {
    throw new IllegalArgumentException("Adding Unit not recognized: " + unit);
  }
  return t.plus(val,uu);
}

private static LocalDateTime add ( LocalDateTime t , int val , String unit ) { ChronoUnit uu = CALENDAR_UNITS . get ( unit ) ; if ( null == uu ) { throw new IllegalArgumentException ( "Adding Unit not recognized: " + unit ) ; } return t . plus ( val , uu ) ; }
returns a modified time by " adding " the specified value of units
