anchor.diff:  
   adjust_status(IF, operstate, A, B) ->
       {adjust_operstate(A, IF), adjust_operstate(B, IF)};
  -adjust_status(_, A, B) ->
  +adjust_status(_, _, A, B) ->
       {A, B}.
   
   adjust_operstate(undefined,  _) -> down;
  
positive.code:          terminate/2,
           code_change/3]).
  
  -record(iface, {name,
                  status = down,
                  opts = []}).
  
negative.code:              poll_ref}).
  
  -define(BADARG, {?MODULE, '__BADARG__'}).
  -define(POLL_INTERVAL, 3000).  % we only poll if netlink_drv isn't present
  
  is_network_up() ->
      call(is_network_up).
  