Reminds me a lot about 'optional chaining' in Swift (among other languages I'm sure), at least on a superficial level. What I'm not sure about at the moment is

Reminds me a lot about 'optional chaining' in Swift (among other languages I'm sure), at least on a superficial level. What I'm not sure about at the moment is where best practices suggest you should use them–it seems like some functions are written to accept optionals, while others are not, and it's not clear why to me.