class MAIN is
  main is
    s ::= #STACK{INT};
    #OUT + "push values...\n";
    s.push(3);
    s.push(2);
    s.push(1);
    s.push(0);
    #OUT + "retrieving them...\n";
    loop
      #OUT + s.pop + "\n";
    until!(s.is_empty); end;
  end;
end;