<p>
Write a function that transforms the <code>start</code> data structure into the <code>expected</code> data structure. Your function should not modify the original data structure -- instead, it should return a new structure.
</p>
<p>
Your solution will be judged using the following criteria:
<ul>
<li>correctness</li>
<li>efficiency</li>
<li>code quality</li>
<li>code size</li>
<li>copypasta (we only want to see YOUR code!)</li>
</ul>
</p>
<p>
We recommend spending 30 minutes on this problem.
</p>
<p>
<b>Bonus:</b> Use only methods from <code>Object</code> and <code>Array</code> instead of <code>for</code> or <code>while</code> loops.
</p>
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