span class="st">'data.frame'</span><span class="op">:</span><span class="st">    </span><span class="dv">139</span> obs. of  <span class="dv">17</span> variables<span class="op">:</span></a>
<a class="sourceLine" id="cb2-8" data-line-number="8"><span class="st">  </span>..<span class="op">$</span><span class="st"> </span><span class="er">:</span><span class="st">'data.frame'</span><span class="op">:</span><span class="st">    </span><span class="dv">54</span> obs. of  <span class="dv">17</span> variables<sp