anchor.diff:                      match members.[i] with
                       | :? PropertyInfo as p -> p.GetValue t
                       | :? FieldInfo as f -> f.GetValue t
  -                    | _ -> invalidOp "internal error on serializing '%O'." typeof<'T>
  +                    | _ -> invalidOp <| sprintf "internal error on serializing '%O'." typeof<'T>
   
                   picklers.[i].UntypedWrite w names.[i] value
   
  
positive.code:                     match members.[i] with
                      | :? PropertyInfo as p -> p.GetValue t
                      | :? FieldInfo as f -> f.GetValue t
                      | _ -> invalidOp "internal error on visiting '%O'." typeof<'T>
  
                  picklers.[i].UntypedAccept v value
  
  
negative.code:                     let o' = picklers.[i].UntypedClone c o
                      f.SetValue(t', o')
  
                  | _ -> invalidOp <| sprintf "internal error on cloning '%O'." typeof<'T>
  
              run onSerialized t c
              run onDeserialized t' c
  