an> <span class="op">&lt;-</span> <span class="va">p1</span> <span class="op"><a href="https://magrittr.tidyverse.org/reference/pipe.html" class="external-link">%&gt;%</a></span> <span class="fu">add_feature_contiguity_constraints</span><span class="op">(</span>data <span class="op">=</span> <span class="va">cm4</span><span class="op">)</span></span></span>
<span class="r-in"><span></span></span>
<span class="r-in"><span><span class="co"># solve problems</span></span></span>
<span class="r-in"><span><span c