anchor.diff:  getifaddrs(Filter, Namespace)
     when is_function(Filter, 1) andalso is_list(Namespace) ->
       do_getifaddrs(Filter, fun() -> getifaddrs(Namespace) end).
  +
  +-dialyzer({no_return, do_getifaddrs/2}).
   
   do_getifaddrs(Filter, GetIfAddrs) ->
       case GetIfAddrs() of
  
positive.code: if_index2name(Idx) when is_integer(Idx) ->
      prim_net:if_index2name(Idx).
  -else.
  -dialyzer({nowarn_function, if_index2name/1}).
  if_index2name(Idx) when is_integer(Idx) ->
      erlang:error(notsup).
  -endif.
  
negative.code:       Namespace :: file:filename_all(),
        IfAddrs   :: [ifaddrs()],
        Reason    :: term().
  
  -dialyzer({no_return, getifaddrs/2}).
  
  getifaddrs(Filter, Namespace)
    when (is_atom(Filter) orelse is_map(Filter)) andalso is_list(Namespace) ->
  