 HAL trait may look like:</p>

<div class="example-wrap"><pre class="rust rust-example-rendered">
<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">nb</span>;

<span class="doccomment">/// A serial interface</span>
<span class="kw">pub</span> <span class="kw">trait</span> <span class="ident">Serial</span> {
    <span class="doccomment">/// Error type associated to this serial interface</span>
    <span class="kw">type</span> <span class="ident">Error</span>;

    <span class="