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