title: Is it possible to have a private constructor in dart?
body: <p>I'm able to do something like the following in TypeScript</p>
  
  <pre><code>class Foo {
    private constructor () {}
  }
  </code></pre>
  
  <p>so this <code>constructor</code> is accessible only from inside the class itself.</p>
  
  <p>How to achieve the same functionality in Dart?</p>