Namespacing
As we add more validators, we’re going to want to have some kind of organization scheme so that we can keep track of our types and not worry about name collisions with other objects. Instead of putting lots of different names into the global namespace, let’s wrap up our objects into a namespace.
In this example, we’ll move all validator-related entities into a namespace called Validation. Because we want the interfaces and classes here to be visible outside the namespace, we preface