suspend fun foo() {
  doSomething()
  callASuspendFunction()
  doSomethingElse()
}

I'm looking for advice on how to get started learning Android Things SDK and Android Bluetooth.
I need some piece of hardware to test any Android code I write.

Do you know of any board I could buy for test purposes. Ideally, I'd want to be 
able to connect with it via Bluetooth LE then maybe make some lights flash or 
something else happen on the board.

I looked at adafruit.com but that seemed to be about programming the board.
I want to program Android phone to talk to the board.

I have this following navigation xml whose design view shows ListFragment overlapping ItemFragment.  If I test it ListFragment goes away and is not replaced by ItemFragment(onCeate is not invoked).  My fragments live in MainActivity which is a ConstraintLayout containing a FragmentContainerView referencing my navigation xml file

<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    app:startDestination="@id/list_dest">

<fragment 
    android:id=“@+id/list_dest”
    android:name=“com.example.navigation.ListFragment”
    tools:layout=“@layout/fragment_list”>
        <action
            android:id=“@+id/next_action”
            app:destination=“@id/item_dest” />
 </fragment>
...

I am trying to use safeArgs plugin.  After a list item is selected I do
val action = ListFragmentDirections.nextAction("myName", "myDesc")
findNavController().navigate(action)

Yes, my design view of mobile_nav.xml complained.  But I reference it in my activity:
androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
        <androidx.fragment.app.FragmentContainerView
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
...

sealed class ImageSource {
  data class Resource(@DrawableRes resourceId: Int) : ImageSource()
  data class Web(url: String) : ImageSource()
}