public Iterator<RecordID> sortedScan(){
  LeafNode firstLeaf=new LeafNode(this,firstLeafPageNum);
  return new BPlusIterator(firstLeaf);
}

public Iterator < RecordID > sortedScan ( ) { LeafNode firstLeaf = new LeafNode ( this , firstLeafPageNum ) ; return new BPlusIterator ( firstLeaf ) ; }
performs a sorted scan from the beginning of the index to the end .
