hashKey</code> property to each item in the array. This property is then used as a key to associated DOM elements
with the corresponding item in the array by identity. Moving the same object in array would move the DOM
element in the same way in the DOM.</p>
<p>For example: <code>item in items track by item.id</code> is a typical pattern when the items come from the database. In this
case the object identity does not matter. Two objects are considered equivalent as long as their <code>id</code>
property is 