an class="r-in"><span><span class="co"># note how the result is grouped by all non-rvar input columns,</span></span></span>
<span class="r-in"><span><span class="co"># and nested indices in `b` are converted into columns.</span></span></span>
<span class="r-in"><span><span class="va">draws_df</span> <span class="op">=</span> <span class="va">rvar_df</span> <span class="op"><a href="https://magrittr.tidyverse.org/reference/pipe.html" class="external-link">%&gt;%</a></span></span></span>
<span class="r-in"><s