span class="r-pr">#&gt;</span> , ,  = 2</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> </span>
<span class="r-out co"><span class="r-pr">#&gt;</span>    </span>
<span class="r-out co"><span class="r-pr">#&gt;</span>     2 3</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>   0 0 0</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>   1 0 4</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> </span>
<span class="r-in"><span><span class="co"># expanded covariates