function &AMP_initBuffer($header = '', $footer = '', $delimiter = "\n\n")
 {
     require_once 'AMP/Content/Buffer.php';
     $buffer = new AMP_Content_Buffer();
     if ($header) {
         $buffer->set_header($header);
     }
     if ($footer) {
         $buffer->set_footer($footer);
     }
     if ($delimiter) {
         $buffer->set_delimiter($delimiter);
     }
     return $buffer;
 }