Creating a coroutine to call a service

Now it's a good time to add a call to a service. To start with something simple, we will use Java's DocumentBuilder to call an RSS feed for us. First, we will add a variable to hold the DocumentBuilderFactory below where we put the dispatcher:

private val dispatcher = newSingleThreadContext(name = "ServiceCall")
private val factory = DocumentBuilderFactory.newInstance()

The second step is to create a function that will do the actual call:

private fun fetchRssHeadlines(): List<String> {
  val builder = factory.newDocumentBuilder()
  val xml = builder.parse("https://www.npr.org/rss/rss.php?id=1001")
  return emptyList()
}

Notice how the function is, for now, returning an empty list of strings after calling the feed. The idea is to implement this function so that it returns the headlines of the given feed. But...