<?php declare(strict_types = 1);

/** @var DateTime|DateInterval $command */
$command = new DateTime();

switch ($command::class) {
	case DateTime::class:
		// Call to an undefined method DateInterval\|DateTime::getTimestamp().
                var_dump($command->getTimestamp());
		break;
	case DateInterval::class:
		echo " Hello Date Interval " . $command->format('d');

		break;
}

switch (get_class($command)) {
	case DateTime::class:
                // Works
		var_dump($command->getTimestamp());
		break;
	case DateInterval::class:
		echo " Hello Date Interval " . $command->format('d');

		break;
}