n">
    <p>Add rows to <code>df</code> to complete all combinations of
    columns <code>.x</code> and <code>.y</code>. Importantly, this function observes and
    maintains any groups created by <code><a href='https://dplyr.tidyverse.org/reference/group_by.html'>dplyr::group_by()</a></code>.</p>
    </div>

    <pre class="usage"><span class='fu'>add_missing_combinations</span><span class='op'>(</span><span class='va'>df</span>, <span class='va'>.x</span>, <span class='va'>.y</span><span class='op'>)</span