anchor.diff:  
   -spec inaddr_any([] | [url]) -> string().
   inaddr_any(Options) ->
  -    case get_env_default(ns_server, ipv6, false) of
  +    case misc:is_ipv6() of
           true ->
               case Options of
                   [] ->
  
positive.code: 
  -spec localhost([] | [url]) -> string().
  localhost(Options) ->
      case get_env_default(ns_server, ipv6, false) of
          true ->
              case Options of
                  [] ->
  
negative.code: 
  -spec split_host_port(list(), list()) -> tuple().
  split_host_port(HostPort, DefaultPort) ->
      split_host_port(HostPort, DefaultPort, misc:is_ipv6()).
  
  -spec split_host_port(list(), list(), boolean()) -> tuple().
  split_host_port("[" ++ Rest, DefaultPort, true) ->
  