anchor.diff:      session_return_urls(Session).
   
   session_return_urls(#watts_rsp_session{ referer=R, success_url=undefined,
  -                                       error_url=undefined }) ->
  +                                       failed_url=undefined }) ->
       {R, R};
   session_return_urls(#watts_rsp_session{ success_url=Succ,
  -                                        error_url=undefined }) ->
  +                                        failed_url=undefined }) ->
       {Succ, Succ};
   session_return_urls(#watts_rsp_session{ success_url=Succ,
  -                                        error_url=Err }) ->
  +                                        failed_url=Err }) ->
       {Succ, Err}.
   
   
  
positive.code:           referer = undefined,
            success_url = undefined,
            failed_url = undefined,
            error_url = undefined,
            iss = undefined,
            sub = undefined,
            service_id = undefined,
  
negative.code: -module(watts_rsp).
  -include("watts.hrl").
  -include_lib("public_key/include/public_key.hrl").
  
  -export([new/1,
           exists/1,
  