Consider an Internet of Things (IoT) setup flow for a wireless
light bulb that you control with your app.
This setup flow consists of 4 pages: 
find nearby bulbs, select the bulb that you want to add,
add the bulb, and then complete the setup.
You could orchestrate this behavior from your top-level 
Navigator widget. However, it makes more sense to define a second, 
nested Navigator widget within your SetupFlow widget,
and let the nested Navigator take ownership over the 4 pages
in the setup flow. This delegation of navigation facilitates
greater local control, which is 
generally preferable when developing software.

The following animation shows the app’s behavior:

In this recipe, you implement a four-page IoT setup
flow that maintains its own navigation nested beneath
the top-level Navigator widget.

Prepare for navigation