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 CSE 401: PL/0 - Sample Code
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The following PL/0 program is fib.0. What does it do? 
module main;
    var result:int;

    procedure fib(arg:int);
	var temp:int;
    begin
	if arg <= 0 then result := 0; end;
	if arg  = 1 then result := 1; end;
	if arg  > 1 then
		fib(arg - 1);
		temp := result;
		fib(arg - 2);
		result := result + temp;
	end;
    end fib;

    var n:int;

begin

    n := input;
    while n <> 0 do
        fib(n);
        output := result;
        n := input;
    end;

end main.