A simple if-else widget renderer in an object-oriented way. You can find it similar to Visibility, but with WidgetBuilder usage. With this, the child widget is not put into context until the condition is satisfied.
#code-for-fun
Availability( available: <condition>, childBuilder: (BuildContext context) => <widget>, )
or
Availability( available: <condition>, childBuilder: (BuildContext context) => <widget>, elseBuilder: (BuildContext context) => <another_widget>, )
*** Similar dart code without Availability:
if (<condition>) { return <widget>; } else { return <another_widget>; }