anchor.diff:  
   %% Helpers -------
   
  -listen_open(Domain, ListenOpts, Opts, Fd, Backlog, BindAddr) ->
  +listen_open(Domain, ListenOpts, Opts, ExtraOpts, Backlog, BindAddr) ->
       %% ?DBG([{domain,      Domain},
       %%  	  {listen_opts, ListenOpts},
       %%  	  {opts,        Opts},
  -    %%  	  {fd,          Fd},
  +    %%  	  {extra_opts,  ExtraOpts},
       %%  	  {backlog,     Backlog},
       %%  	  {bind_addr,   BindAddr}]),
  -
  -    ExtraOpts =
  -        if
  -            Fd =:= -1      -> #{};
  -            is_integer(Fd) -> #{fd => Fd};
  -            %% This is an **ugly** hack.
  -            %% inet:connect_options/2 has the bad taste to use this
  -            %% for [{netns, NS}] if that option is used...
  -            %% Which is never called here, but just to keep it the same
  -            %% we use the same for listen!
  -            is_list(Fd)    -> #{netns => Fd}
  -        end,
   
       {SocketOpts, StartOpts0} = setopts_split(socket, Opts),
       %% ?DBG([{socket_opts, SocketOpts}, {start_opts0, StartOpts0}]),
  
positive.code:     error(badarg, [Arg]).
  
  
  socket_open(Domain, Proto, #{fd := FD} = _ExtraOpts, Extra)
    when is_integer(FD) andalso (FD > 0) ->
      Opts = Extra#{dup      => false,
                    domain   => Domain,
                    type     => stream,
                    protocol => Proto},
      %% ?DBG([{fd, FD}, {opts, Opts}]),
      socket:open(FD, Opts);
  socket_open(Domain, Proto, #{netns := NS} = ExtraOpts, Extra)
    when is_list(NS) ->
      Opts = maps:merge(Extra, ExtraOpts),
      %% ?DBG([{netns, NS}, {opts, Opts}]),
      socket:open(Domain, stream, Proto, Opts);
  socket_open(Domain, Proto, _ExtraOpts, Extra) ->
      %% ?DBG([{opts, Extra}]),
      socket:open(Domain, stream, Proto, Extra).
  
  
  terminate(_Reason, State, {_P, _} = P_D) ->
  
negative.code:                     %%
                      Domain = domain(Mod),
                      %% ?DBG({Domain, BindIP}),
                      BindAddr = bind_addr(Domain, BindIP, BindPort, Fd),
                      ExtraOpts = extra_opts(Fd),
  		    %% ?DBG([{listen_opts, ListenOpts}, {backlog, Backlog}]),
                      listen_open(
                        Domain, ListenOpts, StartOpts, ExtraOpts,
                        Backlog, BindAddr)
              end;
          {error, _} = Error ->
              ?badarg_exit(Error)
  