anchor.diff:  
   handle_call({command, Command}, _From, State) ->
       {DriverMod, Ref} = State#state.driver,
  -    DriverMod:command(Ref, Command),
  -    {reply, ok, State}.
  +    Result = DriverMod:command(Ref, Command),
  +    {reply, bool(Result), State}.
   
   handle_cast(Request, _State) -> error({unknown_cast, Request}).
   
  
positive.code:     configure(gpio1_1, T1),
      configure(gpio1_2, T2),
      configure(gpio1_3, T3),
      configure(gpio1_4, T4);
  configure_slot(gpio2, {T1, T2, T3, T4}) ->
      configure(gpio2_1, T1),
      configure(gpio2_2, T2),
      configure(gpio2_3, T3),
      configure(gpio2_4, T4);
  configure_slot(spi1, disable_cs) ->
      configure(ss1, output_1);
  configure_slot(spi1, enable_cs) ->
      configure(ss1, periph_c);
  configure_slot(spi2, disable_cs) ->
      configure(ss2, output_1);
  configure_slot(spi2, enable_cs) ->
      configure(ss2, periph_c).
  
  get(Pin) -> gen_server:call(?MODULE, {command, <<(index(Pin)):8, 2:8>>}).
  
  
negative.code: map_type(output_1) -> 6. % default value 1
  
  map_attr([default]) -> 0.
  
  bool(<<0>>) -> false;
  bool(<<1>>) -> true;
  bool(Val)   -> Val.
  