…ew $parentContext variable
Benefit #1: Can reach custom properties on *all* ancestor contexts, and are not limited to those that haven't been overwritten
(e.g., if we had $index, would now be able to reach all ancestor $index values, not just the closest one)
Benefit #2: Allows discrimination between properties at the current level and properties at the parent level, which
is good because not all custom properties may make sense to inherit.