an> <span class="hljs-literal">NA</span> <span class="hljs-literal">NA</span> <span class="hljs-keyword">...</span>
 $ topic_label       : chr  <span class="hljs-literal">NA</span> <span class="hljs-literal">NA</span> <span class="hljs-literal">NA</span> <span class="hljs-string">"labelc"</span> <span class="hljs-keyword">...</span>
 $ topic_prob        : num  <span class="hljs-literal">NA</span> <span class="hljs-literal">NA</span> <span class="hljs-literal">NA</span> <span class="hljs-number">0.265</span>