anchor.diff:  
                   , client_shared_secret = ClientSharedSecret
   
  -                , token                = {some, TmpTokenCredentials}
  +                , token                = {some, TmpToken}
                   , verifier             = {some, Verifier}
                   , callback             = none
                   },
  
positive.code: 
  -record(request_validation_state,
      { creds_client = none :: hope_option:t(oauth1_credentials:t(client))
      , creds_tmp    = none :: hope_option:t(oauth1_credentials:t(tmp))
      , verifier     = none :: hope_option:t(oauth1_verifier:t())
  
      , result       = none :: hope_option:t(term())
  
negative.code:         end,
      ValidateTmpToken =
          fun (#request_validation_state{}=State1) ->
              case oauth1_credentials:fetch(TmpTokenID)
              of  {error, not_found} ->
                      {error, {unauthorized, token_invalid}}
              ;   {ok, TmpToken} ->
                      State2 =
                          State1#request_validation_state
                          { creds_tmp_tok = {some, TmpToken}
                          },
                      {ok, State2}
              end
          end,
      ValidateVerifier =
          fun (#request_validation_state{}=State1) ->
              case oauth1_verifier:fetch(TmpTokenID)
              of  {error, not_found} ->
                      {error, {unauthorized, verifier_invalid}}
              ;   {ok, Verifier} ->
  