public StoredListIterator<T> establishListScan(boolean random_scan){
  if (isEmpty())   return null;
  StoredListIterator<T> slh=_SLHolderPool.get();
  if (!iterate(random_scan,slh)) {
    slh.release();
    return null;
  }
  return slh;
}

public StoredListIterator < T > establishListScan ( boolean random_scan ) { if ( isEmpty ( ) ) return null ; StoredListIterator < T > slh = _SLHolderPool . get ( ) ; if ( ! iterate ( random_scan , slh ) ) { slh . release ( ) ; return null ; } return slh ; }
establish a scan position . if random scanning supported we select a random position
