title: How to count items that are nested inside a second level groupBy?
body: <pre><code>$bookings = Salon::find(3)-&gt;bookings;
  
  $bookings-&gt;groupBy(['booking_status', function ($item) {
              return \Carbon\Carbon::parse($item['created_at'])-&gt;format('Y-m');
  }])-&gt;toArray();
  </code></pre>
  <p>This gives me below.</p>
  <pre><code>&quot;confirmed&quot; =&gt; [
         &quot;2020-12&quot; =&gt; [
           [],[],[],[]
          ]
  ];
  
  </code></pre>
  <p>However, I am looking for something like this below:</p>
  <pre><code>&quot;confirmed&quot; =&gt; [
         &quot;2020-12&quot; =&gt; 4
  ];
  </code></pre>