at two distinct objects are
mapped to the same DOM element, which is not possible.)  Filters should be applied to the expression,
before specifying a tracking expression.</p>
<p>For example: <code>item in items</code> is equivalent to <code>item in items track by $id(item)</code>. This implies that the DOM elements
will be associated by item identity in the array.</p>
<p>For example: <code>item in items track by $id(item)</code>. A built in <code>$id()</code> function can be used to assign a unique
<code>$$