List<Key> subrecordKeys(long lowTime,long highTime){
  List<Key> keys=new ArrayList<Key>();
  long lowBucketNumber=bucketNumber(lowTime);
  long highBucketNumber=bucketNumber(highTime);
  for (long index=lowBucketNumber; index <= highBucketNumber; index+=this.bucketSize) {
    keys.add(formSubrecordKey(index));
  }
  return keys;
}

List < Key > subrecordKeys ( long lowTime , long highTime ) { List < Key > keys = new ArrayList < Key > ( ) ; long lowBucketNumber = bucketNumber ( lowTime ) ; long highBucketNumber = bucketNumber ( highTime ) ; for ( long index = lowBucketNumber ; index <= highBucketNumber ; index += this . bucketSize ) { keys . add ( formSubrecordKey ( index ) ) ; } return keys ; }
creates a list of keys in the time series
