anchor.diff:     bind(a, lists:last(Pids), A);
   
   bind(a, Pid, A) ->
  -   ioctl(Pid, {a, A});
  +   ioctl_(Pid, {a, A});
   bind(b, Pid, B) ->
  -   ioctl(Pid, {b, B}).
  +   ioctl_(Pid, {b, B}).
   
   %%
   %% make pipeline by binding stages
  
positive.code:   ,monitor/1
    ,demonitor/1
    ,ioctl/2
  
    % pipe i/o interface
    ,call/2
  
negative.code: ioctl(Pid, Req)
   when is_atom(Req) ->
     call(Pid, {ioctl, Req}).
  
  ioctl_(Pid, {Req, Val})
   when is_atom(Req) ->
     send(Pid, {ioctl, Req, Val}), 
     {ok, Val}.
  
  
  %%
  %% monitor process or node. The process receives messages:
  