anchor.diff:  
       ///Applies the given function to each element of the block resize array.
       member this.Iter f =
  -        for i = 0 to active - 1 do
  -            Array.iter f arrays.[i] 
  +        if active > 1
  +        then
  +            for i = 0 to active - 2 do
  +                Array.iter f arrays.[i]
  +        let a = arrays.[active - 1]
  +        let top = countTop count
  +        for i in 0..top do
  +            f a.[i] 
   
   module BlockeResizeArray = 
   
  
positive.code:     ///Builds a new block resize array whose elements are the results of applying the given function to each of the elements of the array.
      member this.Map (f : 'T -> 'U) =
          let result = new BlockResizeArray<'U>()
          let arr = Array.zeroCreate<_> arrays.Length
          for i = 0 to active - 1 do
              arr.[i] <- Array.map f arrays.[i]
          result.SetArrays arr
          result.setCount count
          result.SetActive active
  
negative.code:     let mutable cap = blockSize * arrays.Length
      let mutable nextAllocate = cap
      let mutable active = 1
  
      let countTop c = 
          let tail = count % blockSize 
          if count <> 0 
          then if tail = 0 then blockSize - 1 else tail - 1
          else -1
  
      interface IEnumerable<'T> with
          member this.GetEnumerator () =
              let e = 
  