The example shows how to:
- Access current node data using
${event.data}
- Access current node level using
${event.level}
- Set node children using
${event.children}
For this particular example we've used non homogeneous data (each level have different properties) and you can find example with homogeneous data (self-referencing) in this thread:
Again, these are just examples that can be adapted to your scenario and data.