span class="ident">Read</span><span class="op">&lt;</span><span class="ident">u8</span><span class="op">&gt;</span>,
{
    <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">serial</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">serial</span>);
    <span class="ident">future</span>::<span class="ident">poll_fn</span>(<span class="kw">move</span> <span class="op">|</span><span class="op">|</span> {
        <span class="kw">let</span> <span