title: Update a single key value in a Laravel Illuminate collection
body: <p>I am building a collection from a Facebook API response.</p>
  
  <pre><code>$ads = new \Illuminate\Support\Collection;
  
  if (!$ads-&gt;has($insight[$key])) {
      $ads-&gt;put($insight[$key], [
          'ad_id'                             =&gt; $insight[AdsInsightsFields::AD_ID],
          'ad_name'                           =&gt; $insight[AdsInsightsFields::AD_NAME],
          'ctr'                               =&gt; (float)$insight[AdsInsightsFields::CTR],
          'spend'                             =&gt; (float)$insight[AdsInsightsFields::SPEND],
      ]);
  } else {
      // Increment spend value here.
  }
  </code></pre>
  
  <p>If this were an array, I'd just do this:</p>
  
  <pre><code>$ads[$insight[$key]]['spend'] += $insight[AdsInsightsFields::SPEND];
  </code></pre>
  
  <p>How do I do that on a Collection?</p>