如何检查PHP函数内部是否传入了参数(通过引用传递)？

function checkParameterByReference(&$param) {
    $numArgs = func_num_args();
    if ($numArgs > 0) {
        $args = func_get_args();
        foreach ($args as $arg) {
            if (is_object($arg)) {
                echo "Parameter is an object: " . get_class($arg) . "\n";
            } else {
                echo "Parameter is: " . $arg . "\n";
            }
        }
    } else {
        echo "No parameter passed.\n";
    }
}

$param1 = "Hello";
$param2 = 123;
checkParameterByReference($param1, $param2);

Parameter is: Hello
Parameter is: 123