/// SeekBar(
///   value: 0.5,
///   secondValue: 0.8,
///   progressColor: Colors.blue,
///   secondProgressColor: Colors.orange,
///   onStartTrackingTouch: () {
///     print('onStartTrackingTouch');
///   },
///   onProgressChanged: (value) {
///     print('onProgressChanged:$value');
///   },
///   onStopTrackingTouch: () {
///     print('onStopTrackingTouch');
///   },
/// )