SingleChildBuilder constructor
      const
      SingleChildBuilder({ 
    
- Key? key,
 - required Widget builder(
- BuildContext context,
 - Widget? child
 
 - Widget? child,
 
Creates a widget that delegates its build to a callback.
The builder argument must not be null.
Implementation
const SingleChildBuilder({Key? key, required this.builder, Widget? child})
    : super(key: key, child: child);