title: How to flatten a List?
body: <p>How can I easily flatten a <code>List</code> in Dart?</p>
  
  <p>For example:</p>
  
  <pre class="lang-dart prettyprint-override"><code>var a = [[1, 2, 3], ['a', 'b', 'c'], [true, false, true]];
  var b = [1, 2, 3, 'a', 'b', 'c', true, false, true];
  </code></pre>
  
  <p>How do I turn <code>a</code> into <code>b</code>, i.e. into a single <code>List</code> containing all those values?</p>