anchor.diff:                } = State) ->
     {GunMonitor2, GunConnPid2} = open_gun_connection(Connection),
     {noreply, State#{gun_connection => GunConnPid2, gun_monitor => GunMonitor2}};
  -handle_info({wait_gun_up, Client}, #{gun_connection := GunConn} = State) ->
  +handle_info(timeout, #{gun_connection := GunConn, client := Client} = State) ->
     {ok, Timeout} = application:get_env(apns, timeout),
     case gun:await_up(GunConn, Timeout) of
       {ok, http2} ->
  
positive.code: -type state()        :: #{ connection     := connection()
                           , gun_connection := pid()
                           , gun_monitor    := reference()
                           }.
  
  %%%===================================================================
  
negative.code: %%% gen_server callbacks
  %%%===================================================================
  
  -spec init({connection(), pid()}) -> {ok, State :: state(), timeout()}.
  init({Connection, Client}) ->
    {GunMonitor, GunConnectionPid} = open_gun_connection(Connection),
  
    {ok, #{ connection     => Connection
          , gun_connection => GunConnectionPid
          , gun_monitor    => GunMonitor
          , client         => Client
          }, 0}.
  
  -spec handle_call( Request :: term(), From :: {pid(), term()}, State) ->
    {reply, ok, State}.
  