perator (prefix <code>..&lt;</code>) to create a
partial range of any type that conforms to the <code>Comparable</code> protocol.
This example creates a <code>PartialRangeUpTo&lt;Double&gt;</code> instance that includes
any value less than <code>5.0</code>.</p>
<pre><code class="language-swift">let upToFive = ..&lt;5.0

upToFive.contains(3.14)       // true
upToFive.contains(6.28)       // false
upToFive.contains(5.0)        // false
</code></pre>
<p>You can use this type of partial range of a collection's 