an> <span class="op">+</span></span></span>
<span class="r-in"><span>  <span class="fu"><a href="https://r-tmap.github.io/tmap/reference/tm_shape.html" class="external-link">tm_shape</a></span><span class="op">(</span><span class="va">ny_tracts</span><span class="op">)</span> <span class="op">+</span></span></span>
<span class="r-in"><span>  <span class="fu"><a href="https://r-tmap.github.io/tmap/reference/tm_polygons.html" class="external-link">tm_polygons</a></span><span class="op">(</span>alpha <span cla