lass="op">&lt;-</span> <span class="va">degree</span><span class="op">[</span>, <span class="fu">.</span><span class="op">(</span>degree_count <span class="op">=</span> <span class="va">.N</span><span class="op">)</span>, by <span class="op">=</span> <span class="st">"mcid"</span><span class="op">]</span></span>
<span><span class="va">by_id</span><span class="op">[</span>, <span class="fu">.</span><span class="op">(</span>N_students <span class="op">=</span> <span class="va">.N</span><span class="op">)</spa