title: How to reference another file in Dart?
body: <p>I know you can use the <code>library</code>, <code>import</code> and even <code>#import</code>, but which is correct?</p>
  <p>I have got two files, <code>MainClass.dart</code> and <code>Library.Dart</code>, and I want to add a reference to <code>Library.dart</code> in <code>MainClass.dart</code>. How can I do that?</p>