anchor.diff:  
                   pb.PutInt32 (prevPageNumber) // prev page num.
                   pb.PutInt16 (0) // number of pairs in this page. zero for now. written at end.
  -                // assert pb.Position is 8 (PAGE_OVERHEAD - sizeof(lastInt32))
  +                // assert pb.Position is 8 (LEAF_PAGE_OVERHEAD - sizeof(lastInt32))
               (*
                * one of the following cases must now be true:
                * 
  
positive.code:                 // 2 for the stored count
                  // 5 for the extra ptr we will add at the end, a varint, 5 is worst case
                  // 4 for lastInt32
                  let PAGE_OVERHEAD = 2 + 2 + 5 + 4
  
                  let calcAvailable currentSize couldBeRoot =
                      let basicSize = pageSize - currentSize
  
negative.code:                         if sofar = 0 then
                              first <- i
                              overflows.Clear()
                              sofar <- PARENT_PAGE_OVERHEAD
                          if calcAvailable sofar (nextGeneration.Count = 0) >= neededForInline then
                              sofar <- sofar + k.Length
                          else
  