anchor.diff:  -export_type([credentials/0]).
   -export_type([token/0]).
   
  --record(state, {credentials::betfair:credentials(),
  -                connection, token, keep_alive}).
  +-record(state, {credentials :: betfair:credentials(),
  +                connection :: pid(),
  +                token :: token(),
  +                keep_alive :: number()}).
   
   -type credentials() :: #{username => string(),
                            password => string(),
  
positive.code:          code_change/3
          ]).
  
  -define(SERVER, ?MODULE).
  -define(SCOPE, l).
  
  
negative.code: %%% Internal functions
  %%%===================================================================
  
  -spec request(pid(), reference()) -> {ok, token()} | any().
  request(Connection, Stream) ->
      case gun:await(Connection, Stream) of
          {response, fin, _Status, _Headers} ->
  