anchor.diff:          | Some x -> None
   
   (* ------------------------------------------------------------------------------- *)
  -let bytes_of_key (k : SessionIndex) =
  +let bytes_of_key (k : byte[] * Role * string) =
       let bf = new BinaryFormatter () in
       let m  = new MemoryStream () in
           bf.Serialize(m, k); m.ToArray ()
  
positive.code: 
  (* ------------------------------------------------------------------------------- *)
  let remove self sid role hint =
      let key = bytes_of_key (sid,role,hint) in
      let db  = DB.opendb self.filename in
  
      try
  
negative.code: (* ------------------------------------------------------------------------------- *)
  type StorableSession = SessionInfo * PRF.masterSecret
  type SessionIndex = sessionID * Role * Cert.hint
  
  #if ideal
  type entry = sessionID * Role * Cert.hint * StorableSession
  type t = entry list  
  