loop(Value) ->
         receive
           {get_value, FromPid} when is_pid(FromPid) ->
             FromPid ! {get_value, self(), Value},
             loop(Value);

           {inc_value, FromPid} when is_pid(FromPid) ->
             NewValue = Value + 1,
             FromPid ! {inc_value, self(), NewValue},
             loop(NewValue);

           {UnknownValue, FromPid} when is_pid(FromPid) ->
             FromPid ! {unknown_value, {UnknownValue, self()}},
             loop(Value);