span class="n">source</span><span class="p">,</span> <span class="nv">target</span><span class="p">:</span> <span class="n">target</span><span class="p">)</span>
</code></pre>

<p>If you want to include multiple types conforming to <code><a href="Protocols/Differentiable.html">Differentiable</a></code> in the collection, use <code><a href="Structs/AnyDifferentiable.html">AnyDifferentiable</a></code>:</p>
<pre class="highlight swift"><code><span class="k">let</span> <span class="nv">source</span> <span class