title: Access private class or function from other file in flutter
body: <p>I create a widget that have many part. So, it is not good practice to create this widget in one file. So that, I rearrange in many file. I make private these widgets(part), so that, these can't be accessed in other file. I want to access these widgets only in root widget.(or private classes can be accessed in its directory files) How can I do it?</p>
  <pre><code>// homepage/homepage.dart
  
  import 'package:flutter/material.dart';
  
  class Homepage extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return Container(
        child: Column(
          children: [
            _Part1(),
            _Part2(),
          ],
        ),
      );
    }
  }
  
  </code></pre>
  <pre><code>// homepage/part1.dart
  import 'package:flutter/material.dart';
  
  class _Part1 extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return Container(
        
      );
    }
  }
  </code></pre>
  <pre><code>// homepage/part2.dart
  import 'package:flutter/material.dart';
  
  class _Part2 extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return Container(
        
      );
    }
  }
  </code></pre>