<?php function c_alert(string $html_message, string $type, ?string $icon = null): void { ?>
<div class="alert alert-<?= htmlentities($type) ?>">
<?php if ($icon !== null): ?>
<i class="glyphicon glyphicon-<?= htmlentities($icon) ?>"></i>
<?php endif; ?>
<?= $html_message ?>
</div>
<?php }