message: Make `add_node` return reference to inserted node as suggest by
diff: @@ -101,10 +101,14 @@ impl Network {
  }
  /// Creates a new networking node on the network.
  - async fn add_node(&mut self) -> anyhow::Result<()> {
  + async fn add_node(&mut self) -> anyhow::Result<&mut reactor::Runner<TestReactor>> {
  let runner = reactor::Runner::new(small_network::Config::default_on_port(11223)).await?;
  self.nodes.push(runner);
  - Ok(())
  +
  + Ok(self
  + .nodes
  + .last_mut()
  + .expect("vector cannot be empty after insertion"))
  }
  /// Crank all runners once, returning the number of events processed.
  