Multiple mutable references can be problematic though: <a href="http:&#x2F;&#x2F;manishearth.github.io&#x2F;blog&#x2F;2015&#x2F;05&#x2F;17&#x2F;the-problem-with-shared-mutability&#x2F;" rel="nofollow">http:&#x2F;&#x2F;manishearth.github.io&#x2F;blog&#x2F;2015&#x2F;05&#x2F;17&#x2F;the-problem-wit...</a><p>(Rust has Cell&#x2F;RefCell if you need this, though)