anchor.diff:  
               // get active stream information for stream 0.  currently we ignore other streams (will log a warning below if the declaration
               // uses data from non-stream 0).
  -            let mutable vb:VertexBuffer = null
               let mutable offsetBytes = 0
               let mutable strideBytes = 0
   
  
positive.code:                 |> List.map (fun i ->
                      let texName = sprintf "%s_texture%d.dds" sbasename i
                      let texPath = Path.Combine(baseDir, texName)
                      if saveTexture(i, texPath) then
                          i,(texName,texPath)
                      else
  
negative.code: 
              // index buffer
              if sd.IndexBuffer = 0n then failwith "Index buffer is null"
              ib <- new IndexBuffer(sd.IndexBuffer) // do not dispose, native code owns it
              let ibDesc = ib.Description
              log.Info"IndexBuffer: Format: %A, Usage: %A, Pool: %A, Size: %d" ibDesc.Format ibDesc.Usage ibDesc.Pool ibDesc.Size
  
  