[culebron21]

Somehow at some point lifetimes started clicking for me. I think the key was when I understood that in a function, not everything needs the same lifetime. e.g.

    struct MyRef<'a> { item: &'a i64 }
    struct MyType { items: Vec<i64> }
    impl MyType {
        fn get_some_ref(&self, key: &usize) -> MyRef<'a> {
            MyRef { item: &self.items[key] }
        }
    }

the function this way is incorrect. When I was a beginner, I would have thought that every & in the signature needed a lifetime. In a slightly complicated code, the borrow checker then demanded lifetimes everywhere, they'd infect everything, but the code would still never compile.

Then I understood that not everything needs to be tied to the same lifetime. In this example, MyRef should be tied to the MyStruct, but not to the `key`:

        fn get_some_ref<'a>(&'a self, key: &usize) -> MyRef<'a>