You can use `if/else` blocks to dynamically change content depending on which product or service has been purchased.

For example, the below snippet displays a different message depending on which product has been purchased (more
specifically, the content changes based on the _first_ product on the invoice).

```bash
{% if invoice.line_items[0].item_id == 1 %}
   You purchased product ONE!
{% else %}
   You purchased something else.
{% endif %}
```