if you have a Dart class that only contains static methods and constants , most likey you want to make the class to be non-instantiable. However, even if you don't provide any constructor,
Dart creates an empty constructor for the class by default.
Create Private Constructor to Prevent Instantiation
The solution is creating a private constructor. By declaring a private constructor, Flutter no longer creates the defaut constructor. To make the contructor private ,
you need to user _(underscore) which means private
