f sequences, concatenated.</p>

<p>In this example, an array of three ranges is flattened so that the
elements of each range can be iterated in turn.</p>

<pre><code class="language-swift">let ranges = [0..&lt;3, 8..&lt;10, 15..&lt;17]

// A for-in loop over &#39;ranges&#39; accesses each range:
for range in ranges {
  print(range)
}
// Prints &quot;0..&lt;3&quot;
// Prints &quot;8..&lt;10&quot;
// Prints &quot;15..&lt;17&quot;

// Use &#39;joined()&#39; to access each element of each range:
for index in ra