title: Dart/Flutter How to initialize a List inside a Map?
body: <p>How can I initialize a list inside a map?</p>
  
  <pre><code>Map&lt;String,Map&lt;int,List&lt;String&gt;&gt;&gt; myMapList = Map();
  </code></pre>
  
  <p>I get an error :</p>
  
  <pre><code>The method '[]' was called on null.
  I/flutter (16433): Receiver: null
  I/flutter (16433): Tried calling: [](9)
  </code></pre>