anchor.diff:                      let allowanceForRootNode = if couldBeRoot then sizeof<int32> else 0 // first/last Leaf, lastInt32 already
                       basicSize - allowanceForRootNode
   
  -                let buildParentPage stop start (overflows:Map<int,int32>) =
  +                let buildParentPage stop start (overflows:Map<byte[],int32>) =
                       // assert stop > start
                       let countKeys = stop - start
                       pb.Reset ()
  
positive.code:                     // note loop bounds
                      for q in start .. (stop-1) do
                          let k = snd children.[q]
                          match overflows.TryFind(q) with
                          | Some pg ->
                              pb.PutByte(FLAG_OVERFLOW)
                              pb.PutVarint(int64 k.Length)
  
negative.code:             nextPage:int; 
              boundaryPage:int; 
              //children:(int32*byte[]); 
              overflows:Map<byte[],int32>;
          }
  
      let Create(fs:Stream, pageManager:IPages, csr:ICursor) :int32 = 
  