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header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
// Date in the past header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
// always modified header("Cache-Control: no-store, no-cache, must-revalidate");
// HTTP/1.1 header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
// HTTP/1.0