@Override public Object clone(){
  ArrayList<BinaryItem> items=new ArrayList<BinaryItem>(m_items);
  return new FrequentBinaryItemSet(items,m_support);
}

@ Override public Object clone ( ) { ArrayList < BinaryItem > items = new ArrayList < BinaryItem > ( m_items ) ; return new FrequentBinaryItemSet ( items , m_support ) ; }
make a copy of this item set .
