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: %%%
  
  %%%---- HMAC
  
  -type hmac_hash_algorithm() ::  sha1() | sha2() | sha3() | compatibility_only_hash().
  
  %%%---- hmac/3,4
  
  
negative.code:               stream_state/0,
                hmac_state/0,
                hash_state/0,
                crypto_state/0,
                mac_state/0
               ]).
  
  %% Private. For tests.
  