anchor.diff:  
       let rec private skipCell count (list : LazyList<'T>) =
           if count = 0 then
  -            getCell list
  +            list.Value
           else
               match list.Value with
               | Cons (_, tl) ->
  
positive.code:         checkNonNull "list" list
  
          let rec lengthAux acc (list : LazyList<'T>) =
              match getCell list with
              | Empty ->
                  int acc
              | Cons (_, tl) ->
  
negative.code:         assert (not <| isNull list)
          Cons (value, list)
  
      /// Alias for LazyList.CreateLazy.
      let inline private lzy cellCreator : LazyList<'T> =
          LazyList<_>.CreateLazy cellCreator
  
      /// Apply the given function to successive elements of the list, returning the first
      /// result where function returns <c>Some(x)</c> for some x.
  