Allows one to store a header struct and a vector all inline in the same memory on the heap and share weak versions for minimizing random lookups in data structures
The HeaderVec implements Deref. This means that you can call methods that h contains directly on the HeaderVec, and you can also access its members directly.
Once I have
let v = HeaderVec::new(h)
, how do I get get a reference to h from v?