title: Flutter: How to generate random boolean value with my own probability?
body: <p>When I use the code :</p>
  
  <pre><code>Random r = new Random();
  r.nextBool();
  </code></pre>
  
  <p>It returns a 50% / 50% probability value (true / false).</p>
  
  <p>How can I generate a true-false value with my own probability like (20% / 35% / 70% ...)?</p>