Dependencies and Hooks

Hi, this is a general question on a user story for carvel kapp. Is there a way to define dependencies or hooks on an app? E.g.,

- Run custom logic before the kapp-controller processing the YAML and deploys the app
- Run custom logic after the kapp-controller marks the app as healthy
- Define a list of selectors (i.e., matchLabels) for apps. All apps matching the selectors must be healthy before kapp-controller deploys the app.

I did not see any similar definition while inspecting the go types for app.