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