title: What is the meaning of `Class._()..property`?
body: <p>What does <code>._()..</code> mean in the following code?</p>
  
  <pre class="lang-dart prettyprint-override"><code>class CounterState {
    int counter;
  
    CounterState._();
  
    factory CounterState.init() {
      return CounterState._()..counter = 0;
    }
  }
  </code></pre>
  
  <p>More precisely - what do the two dots <code>..</code> mean past <code>._()</code>?</p>