anchor.diff:          let mutable capacity = 0n
           let mutable length = 0n
           let mutable count = 0u
  -        let mutable offsets = System.Collections.Generic.List<nativeint>()
   
           let handle = 
               let handle = NativePtr.alloc 1
  
positive.code:             let ptr = x.HandleCommands + length
              f ptr
              let id = count
              offsets.Add length
              length <- e
              count <- count + 1u
              x.HandleCount <- count
              id
  
          [<MethodImpl(MethodImplOptions.NoInlining)>]
          member private x.Append<'a when 'a : unmanaged>(data : byref<'a>) =
  
negative.code:                     capacity <- 0n
                      length <- 0n
                      count <- 0u
                      f
                  )
  
  