title: Extract only raw ids from an Eloquent collection
body: <p>I need to get an <strong>array of integers</strong>, which will contain raw ids of Eloquent records. The following query</p>
  
  <pre><code>Quote::select('id')-&gt;get();
  </code></pre>
  
  <p>gets an eloquent collection instead of an array of integers. How to modify it, so it meets my requirements?</p>