anchor.diff:  
   %%
   %% spawn pipe functor stage
  -%%   Options
  -%%     link
  -%%     monitor
  -%%     {init, Fun()}
   -spec(spawn/1         :: (function()) -> pid()).
   -spec(spawn_link/1    :: (function()) -> pid()).
   -spec(spawn_monitor/1 :: (function()) -> {pid(), reference()}).
  --spec(spawn_opts/2    :: (function(), list()) -> pid() | {pid(), reference()}).
   
   spawn(Fun) ->
      erlang:spawn(fun() -> pipe_loop(Fun, undefined, undefined) end).
  
positive.code:   ,spawn/1
    ,spawn_link/1
    ,spawn_monitor/1
    ,spawn_opts/2
    ,bind/2
    ,bind/3
    ,make/1
  
negative.code: 
  spawn_monitor(Fun) ->
     erlang:spawn_monitor(fun() -> pipe_loop(Fun, undefined, undefined) end).
  
  %%
  %% bind process to pipeline
  