The Singleton Pattern is probably the most well-known design patterns that came out of Gang of Four's book Design Patterns: Elements of Reusable Object-Oriented Software. This pattern is one of the creational patterns, and basically, it ensures that only one object of a particular class is created and shared among other members of the system.
In the same time when first object-oriented languages were emerging, another concept inspired by general relativity and quantum mechanics was taking shape - actor model.
Back in the day when I was a young developer, I was using output parameters. Then I figured out it is somewhat complicated to test functions with output parameters, and that their use is clunky at best. Also, out parameters don't work with async function, because of CLR limitations.