anchor.diff:  
   open System
   open System.IO
  -open System.Collections.Generic
   
   open Zumero.LSM
   
  
positive.code:         let sortfunc (a:ICursor) (b:ICursor) = b.KeyCompare(a.Key())
          find sortfunc
  
      static member Create(_subcursors:IEnumerable<ICursor>) :ICursor =
          upcast (MultiCursor _subcursors)
                 
      static member Create([<ParamArray>] _subcursors: ICursor[]) :ICursor =
  
negative.code: 
  type private Direction = FORWARD=0 | BACKWARD=1 | WANDERING=2
  
  type MultiCursor private (_subcursors:seq<ICursor>) =
      let subcursors = List.ofSeq _subcursors
      let mutable cur:ICursor option = None
      let mutable dir = Direction.WANDERING
  