anchor.diff:      // root page
       // age
       // number of pairs
  -    // each pair is startBlock,lastBlock
  +    // each pair is startBlock,countBlocks
       // all in varints
   
       let writeHeader hdr =
  
positive.code:             if specificSize > 0 then
                  if List.isEmpty freeBlocks || specificSize > (List.head freeBlocks).CountPages then
                      let newBlk = PageBlock(nextPage, nextPage+specificSize-1) 
                      nextPage <- nextPage + specificSize + WASTE_PAGES_AFTER_EACH_BLOCK
                      //printfn "newBlk: %A" newBlk
                      newBlk
                  else
  
negative.code:             else
                  let size = settings.PagesPerBlock
                  let newBlk = PageBlock(nextPage, nextPage+size-1) 
                  nextPage <- nextPage + size
                  //printfn "newBlk: %A" newBlk
                  newBlk
              )
  