handleLegendItemTapped method 
    
      
  
void
handleLegendItemTapped(
 - LegendItem item, 
- bool isToggled
)override
     
    
    
  Implementation
  @override
void handleLegendItemTapped(LegendItem item, bool isToggled) {
  super.handleLegendItemTapped(item, isToggled);
  final ChartLegendItem legendItem = item as ChartLegendItem;
  if (legendItem.pointIndex < segments.length) {
    segmentAt(legendItem.pointIndex).isVisible = !isToggled;
  }
  legendItem.onToggled?.call();
  animationType = AnimationType.realtime;
  canUpdateOrCreateSegments = true;
  markNeedsLayout();
}