n class="identifier">my_expression</span>
        <span class="special">=</span> <span class="identifier">a</span> <span class="special">+</span> <span class="identifier">b</span> <span class="special">-</span>
        <span class="identifier">c</span><span class="special">;</span></code>
      </p>
<p>
        unless you're absolutely sure that the lifetimes of <code class="computeroutput"><span class="identifier">a</span></code>,
        <code class="computeroutput"><span class="identifier">b</span></code