Scenic.ViewPort.set_root

You're seeing just the function set_root, go back to Scenic.ViewPort module for more information.
Link to this function

set_root(viewport, scene, args \\ nil)

View Source

Specs

set_root(viewport :: t(), scene :: atom(), args :: any()) :: :ok

Set the root scene/graph of the ViewPort.

This will stop the currently running scene, including all of it's child components. Then it starts the new scene including all of it's child components.