anchor.diff:    {gpio_pin, Pin}.
   
   
  -%% @doc value_change(Old, New)
  +%% value_change(Old, New)
   %% value_change(0, 1) ->
   %%   raising;
   %% value_change(1, 0) ->
  
positive.code: -behaviour(gen_server).
  
  %% API
  -export([start_link/2,
           release/1,
           write/2,
           read/1,
  
negative.code: %% value_change(_, _) ->
  %%   no_change.
  
  %%% Local Variables:
  %%% erlang-indent-level: 2
  %%% End:
  