 {
  // Get the system temp directory.
  var systemTempDir = Directory.systemTemp;

  // List directory contents, recursing into sub-directories,
  // but not following symbolic links.
  systemTempDir.list(recursive: true, followLinks: false)
    .listen((FileSystemEntity entity) {
      print(entity.path);
    });
}
</code></pre>
<h2 id="the-use-of-futures">The use of Futures</h2>
<p>I/O operations can block a program for some period of time while it waits for
the operation to complete. To avoid this, all
