program five;
   
   unit A: process(node: integer, p: pq);
       unit finish: procedure; end finish;
   begin
        return;

        call p.update(false);
        accept finish;    
   end A;

   unit B: process(node:integer, p:pq, q:pq);
        var aux: boolean;
         unit finish: procedure; end finish;
   begin
        return;
        
        call q.update(true);
        aux := q.readval;
        call p.update(aux);
        accept finish;
   end B;
  
    unit pq: process(node:integer);
       var value : Boolean;

        unit readval: function: Boolean;
        begin
             result := value;
        end readval;

        unit update: procedure(arg: boolean);
        begin
              value := arg
        end update;
    begin
          value := false;
           return;

           do
               accept readval, update;
           od;
    end pq;

   var aa: A, bb: B, p,q: pq;
begin
    p := new pq(0);
    q := new pq(0);
    aa := new A(0,p);
    bb := new B (0, p, q);

    resume(p);
    resume(q);
    resume(aa);
    resume(bb);
    
    call aa.finish;
    call bb.finish;

    if p.readval then writeln ("p is TRUE") else writeln("p is FALSE") fi;
    call endrun
end


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