The Concept of Nothing

Vortex does not have a concept of NULL. There are many times when 'nothing' needs to be returned, such as calling

<$next = (xmlTreeGetNext($node))>

when there is no next for node. In these cases, it actually returns nothing (no values). This means next will be set just the same as if you had run

<$next = >

"Nothing" compares equal to the empty string, so it's possible to do things like

<$node = (xmlTreeGetFirstChild($parent))>
<while $node neq ''>
    <$name = (xmlTreeGetName($node))>
    name: $name
    <$node = (xmlTreeGetNext($node))>
</while>