y on nightly though</span>

    <span class="ident">hint</span> <span class="op">=</span><span class="question-mark">?</span> <span class="ident">opt_help</span>; <span class="comment">// &lt;-- &quot;optional&quot; attachment, get displayed only if `Some`</span>
                      <span class="comment">//     must be single `Option` expression</span>

    <span class="ident">note</span> <span class="op">=</span><span class="question-mark">?</span> <span class="ident">note_span</span> <span class="op">=<