n><span class="va">x5</span>, na_values <span class="op">=</span> <span class="fl">4</span><span class="op">)</span></span>
<span><span class="co">#&gt; &lt;declared&lt;numeric&gt;[4]&gt;</span></span>
<span><span class="co">#&gt; [1]     1     2     3 NA(4)</span></span>
<span><span class="co">#&gt; Missing values: 4</span></span>
<span><span class="co">#&gt;</span></span>
<span><span class="co">#&gt; Labels:</span></span>
<span><span class="co">#&gt;  value    label</span></span>
<span><span class="co">#&