'>5</span>, <span class='number'>7</span>);</pre>

<p>However it&#39;s often the case that Rust isn&#39;t sufficiently smart to prove that
multiple borrows are disjoint. <em>This does not mean it is fundamentally illegal
to make such a borrow</em>, just that Rust isn&#39;t as smart as you want.</p>

<p>To simplify things, we can model variables as a fake type of reference: <em>owned</em>
references. Owned references have much the same semantics as mutable references:
they can be re-borrowed in a mutable or 