anchor.diff:  
   -record(request_validation_state,
       { creds_client = none :: hope_option:t(oauth1_credentials:t(client))
  -    , creds_tmp_tok= none :: hope_option:t(oauth1_credentials:t(tmp))
  +    , creds_token  = none :: hope_option:t(oauth1_credentials:t(tmp))
       , verifier     = none :: hope_option:t(oauth1_verifier:t())
   
       , result       = none :: hope_option:t(any())
  
positive.code: 
  -spec make_validate_consumer_key(oauth1_credentials:id(client)) ->
      request_validator(any()).
  make_validate_consumer_key(ConsumerKey) ->
      fun (#request_validation_state{}=State1) ->
          case oauth1_credentials:fetch(ConsumerKey)
          of  {error, not_found} ->
                  {error, {unauthorized, client_credentials_invalid}}
          ;   {error, _}=Error ->
                  Error
          ;   {ok, ClientCredentials} ->
                  State2 =
                      State1#request_validation_state
                      { creds_client = {some, ClientCredentials}
                      },
                  {ok, State2}
          end
      end.
  
  -spec make_validate_tmp_token(oauth1_credentials:id(tmp)) ->
      request_validator(any()).
  make_validate_tmp_token(TmpTokenID) ->
      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.
  
  
negative.code:     , signature_method = _SignatureMethod
      , timestamp        = _Timestamp
      , nonce            = _Nonce
      , token            = _TokenID
      }
  ) ->
      ?not_implemented.
  
  -spec make_validate_nonce(oauth1_nonce:t()) ->
      request_validator(any()).
  