code: private void addLeafDelta(Segment10 segment,
                              int pid, 
                              int nextPid,
                              int address,
                              int length)
    {
      Page10 page = _pageMap.get(pid);
      
      if (page != null && page.sequence() < segment.sequence()) {
        return;
      }
      
      if (page != null) {
        page.addDelta(address, length);
      }
    }
docs: Adds a new leaf delta to the page list.
  
  Because pages are added in order, each new page overrides the older one.