anchor.diff:          
       let blank px = 
         let b = g.CreateBlankNode ()
  -      triples (qn b.InternalID,px)
  +      
  +      triples (b,px)
         |> ignore
         b :> INode
       
  
positive.code:     let prov = "http://www.w3.org/ns/prov#"
      let owl = "http://www.w3.org/2002/07/owl#"
      let bas = "http://nice.org.uk/ns/prov#"
      
    
    let fromActivity (act:Activity) =
      use g = new Graph ()
      let literal s =
        g.CreateLiteralNode s :> INode
  
  
negative.code:  
    type Uri =
      | Uri of string * string
      with static member commit r c = Uri ("",sprintf "commit-%s" (short c r))
           static member identity (c:LibGit2Sharp.Commit) = Uri ("",sprintf "user-%s" c.Author.Email)
           static member versionedcontent c = Uri ("",sprintf "file-%s" c)
           static member individual (r,f:LibGit2Sharp.TreeEntryChanges) = Uri ("",f.Path)
           override x.ToString () = match x with | Uri (p,s) -> sprintf "base:%s" s 
           
    type FileVersion = {
      Id : Uri
  