anchor.diff:                  i <- i + 1
           if i>len then result else (xlen - ylen)
   
  -    let compareWithin (x:byte[],off,xlen,y:byte[]) =
  +    let CompareWithin (x:byte[],off,xlen,y:byte[]) =
           let ylen = y.Length
           let len = if xlen<ylen then xlen else ylen
           let mutable i = 0
  
positive.code:             ok
  
          let rec searchInParentPage k (ptrs:uint32[]) (keys:byte[][]) (i:uint32) :uint32 =
              let cmp = ByteComparer.cmp (k, keys.[int i])
              if cmp>0 then
                  searchInParentPage k ptrs keys (i+1u)
              else
  
negative.code:         cur <- cur + 1
          r
  
      member this.Compare(len, other) =
          ByteComparer.CompareWithin(buf, cur, len, other)
  
      // page type could just be a property
      member this.PageType =
  