In what scenarios would it be justified to continue using PHP 3 instead of upgrading to a newer version like PHP 4?

In scenarios where a legacy system is heavily reliant on PHP 3 and upgrading to a newer version like PHP 4 would require significant time and resources, it may be justified to continue using PHP 3. However, it is important to note that PHP 3 is no longer supported and poses security risks. It is recommended to prioritize upgrading to a newer, supported version of PHP to ensure the security and stability of the system.

// Example code snippet demonstrating the use of PHP 3
$variable = "Hello, PHP 3!";
echo $variable;