[dnautics]

It's also a footgun waiting to happen, because I 150% promise you a junior dev or even senior dev will somewhere forget to pass by value instead of pass by reference. There is a reason why Julia and ruby encourages sigilling functions capable of mutating with a !. That character is not chosen randomly.

Yes, it is also absolutely necessary for expressive A* pathfinding.

This is unnecessary for someone connecting two web APIs. Correctness in most domains is totally worth not having to worry about pass-by-reference defaults.