``if`` ``then`` ``else`` are you standard conditionals.

#### Example 1
```
{% if YES %}
t
{% else %}
f
{% endif %}
```
The boolean operations are limited to ``not`` ``and`` ``or``. Read from left to
right as there is no precedence. If you need precedence use parentheses.

#### Example 2
```
{% if not YES and YES or NO %}
t
{% else %}
f
{% endif %}
```

#### Example 3
```
{% if not( YES and (YES or NO)) %}
t
{% else %}
f
{% endif %}
```

If you need `if` `then` `else` within an expression use the `?` `:` conditional.

#### Example 4
```
{{ YES ? "yes" : "no" }}/{{ NO ? "yes" : "no" }}
```