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-module (select).
-export ([start/0, counter/1, get/0, set/1]).

start () ->
    register (cnt, spawn (?MODULE, counter, [0])).

counter (N) ->
    receive
        increment  -> counter (N+1);
        decrement  -> counter (N-1);
        {set, X}   -> counter (X);
        {get, PID} ->
            PID ! N,
            counter (N);
        stop ->
            ok
    end.
            
get () ->
    cnt ! {get, self()},
    receive
        X -> X
    end.

set (N) -> cnt ! {set, N}.