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<html>
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<body>
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<script type="text/javascript" charset="utf-8">
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// Only prevent unload on the first window close
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var unloadPrevented = false;
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window.onbeforeunload = function() {
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if (!unloadPrevented) {
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unloadPrevented = true;
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return '';
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}
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}
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</script>
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</body>
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</html>
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