>
    <span class="comment">// `Result&lt;(), Error&gt;`</span>
    <span class="macro">block</span><span class="macro">!</span>(<span class="ident">serial</span>.<span class="ident">write</span>(<span class="kw-2">*</span><span class="ident">byte</span>)).<span class="ident">unwrap</span>();
}
</pre></div>
<h3 id="futures" class="section-header"><a href="#futures"><code>futures</code></a></h3>
<p>An example of running two tasks concurrently. First task: blink an LED every
second. Second task: loop back dat