anchor.diff:  %%%
   
   -spec crypto_update(State, Data) -> Result | descriptive_error()
  -                                        when State :: crypto_state(),
  -                                             Data :: iodata(),
  -                                             Result :: binary() .
  +                            when State :: crypto_state(),
  +                                 Data :: iodata(),
  +                                 Result :: binary() .
   crypto_update(State, Data0) ->
       case iolist_to_binary(Data0) of
           <<>> ->
  
positive.code:                            Mac :: binary() .
  
  hmac(Type, Key, Data, MacLength) ->
      ?COMPAT(mac(hmac, Type, Key, Data, MacLength)).
  
  %%%---- hmac_init, hamc_update, hmac_final
  
  -opaque hmac_state() :: binary().
  
  -spec hmac_init(Type, Key) ->
                         State when Type :: hmac_hash_algorithm(),
  
negative.code:          crypto_dyn_iv_init/3,
           crypto_dyn_iv_update/3,
           supports/1,
           mac/3, mac/4, macN/4, macN/5,
           mac_init/2, mac_init/3, mac_update/2, mac_final/1, mac_finalN/2
          ]).
  
  
  