"r-pr">#&gt;</span> </span>
<span class="r-out co"><span class="r-pr">#&gt;</span> $b</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> [1] NA</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> </span>
<span class="r-out co"><span class="r-pr">#&gt;</span> [[3]]</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> [1] 1 2 3</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> </span>
<span class="r-out co"><span class="r-pr">#&gt;</span> $c</span>
<span class="r-out 