*?What is the purpose of the ?? operator in Flutter's Null Safety syntax To assign a default value if a variable is null To safely access a property or method on an object, without throwing an error if the object is null To check if a variable is null before accessing its properties or methods To declare a variable as null *?What is the purpose of the Navigator widget in Flutter To manage the transition between different routes or pages To manage the layout of widgets within a single screen To manage the transition between different functions To manage the transition of the data stored locally