[Paste your code here]

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({super.key});
  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  // Initialize the value here so it can be updated by setState
  double value = 0.8;
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      // Removed const here
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: Slider(
            min: 0.0,
            max: 1.0,
            value: value,
            onChangeStart: (startValue) {
              print('drag start: $startValue');
            },
            onChangeEnd: (endValue) {
              print('drag end: $endValue');
            },
            onChanged: (newValue) {
              // Update the state so the slider moves visually
              setState(() => value = newValue);
              print('value changed: $newValue');
            },
            label: 'Opacity',
            semanticFormatterCallback: (val) {
              print('semanticFormatterCallback: $val');
              return '${(val * 100).toInt()}%';
            },
          ),
        ),
      ),
    );
  }
}