anchor.diff:    {ok, Interfaces} = inet:getifaddrs(),
     nic_ipv4(Device, Interfaces).
   
  +
  +%%--------------------------------------------------------------------
  +%% @doc
  +%% Parse the interface out of the list of interfaces, returning the
  +%% IPv4 address if found.
  +%% @end
  +%%--------------------------------------------------------------------
  +-spec nic_ipv4(Device :: string(), Interfaces :: list())
  +    -> {ok, string()} | {error, not_found}.
   nic_ipv4(_, []) -> {error, not_found};
   nic_ipv4(Device, [{Interface, Opts}|_]) when Interface =:= Device ->
     {ok, nic_ipv4_address(Opts)};
  
positive.code: backend_module(etcd)         -> autocluster_etcd;
  backend_module(_)            -> undefined.
  
  %%--------------------------------------------------------------------
  %% @doc
  %% Return the IP address for the current node for the specified
  
negative.code: -ifdef(TEST).
  -compile(export_all).
  -endif.
  
  -type ifopt() :: {flag,[atom()]} | {addr, inet:ip_address()} |
                   {netmask,inet:ip_address()} | {broadaddr,inet:ip_address()} |
                   {dstaddr,inet:ip_address()} | {hwaddr,[byte()]}.
  
  
  %%--------------------------------------------------------------------
  