anchor.diff:              zip3ToFreshConsTail res t1 t2 t3
               res
           | xs1,xs2,xs3 -> 
  -            invalidArgFmt "list1, list2, list3" 
  -                "{0}\n list1.Length = {1}, list2.Length = {2}, list3.Length = {3}" 
  -                [|SR.GetString SR.listsHadDifferentLengths; xs1.Length; xs2.Length; xs3.Length|]
  +            invalidArg3ListsDifferent "list1" "list2" "list3" xs1.Length xs2.Length xs3.Length 
   
       let rec takeWhileFreshConsTail cons p l =
           match l with
  
positive.code:             let cons2 = freshConsNoTail (f.Invoke(n,h1,h2))
              setFreshConsTail cons cons2
              mapi2ToFreshConsTail (n + 1) cons2 f t1 t2
          | [],xs2 -> 
              invalidArgFmt "list1" 
                  "{0}\nlist1 is {1} elements shorter than list2" 
                  [|SR.GetString SR.listsHadDifferentLengths; xs2.Length|]
          | xs1,[] -> 
              invalidArgFmt "list2" 
                  "{0}\nlist2 is {1} elements shorter than list1" 
                  [|SR.GetString SR.listsHadDifferentLengths; xs1.Length|]
  
      let mapi2 f xs1 xs2 = 
          match xs1,xs2 with
  
negative.code:                 chunkBySizeToFreshConsTail cons resCons chunkSize (i+1) t
  
      let chunkBySize chunkSize list =
          if chunkSize <= 0 then invalidArgInputMustBePositive "chunkSize" chunkSize
          match list with
          | [] -> []
          | head::tail ->
  