anchor.diff:  
   -spec get_proto_dist_type() -> string().
   get_proto_dist_type() ->
  -    case get_env_default(ns_server, ipv6, false) of
  +    case misc:is_ipv6() of
           true ->
               "inet6_tcp";
           false ->
  
positive.code: letrec(Args, F) ->
      erlang:apply(F, [F | Args]).
  
  -spec get_net_family() -> inet:address_family().
  get_net_family() ->
      case get_env_default(ns_server, ipv6, false) of
          true ->
              inet6;
          false ->
  
negative.code: 
  -spec localhost([] | [url]) -> string().
  localhost(Options) ->
      case misc:is_ipv6() of
          true ->
              case Options of
                  [] ->
  