PHP restore_exception_handler() Function

<?php
// Two user-defined exception handler functions
function myException1($exception) {
    echo "[" . __FUNCTION__ . "]" . $exception->getMessage();
}
function myException2($exception) {
    echo "[" . __FUNCTION__ . "]" . $exception->getMessage();
}

set_exception_handler("myException1");
set_exception_handler("myException2");

restore_exception_handler();

// Throw exception
throw new Exception("This triggers the first exception handler...");
?>

[myException1] This triggers the first exception handler...