> B points to C mutably I think you mean that B points to D mutably because C is mutable. The pointing from B to C is locked in place because of the immutabili

> B points to C mutably I think you mean that B points to D mutably because C is mutable. The pointing from B to C is locked in place because of the immutability of B. However, C is free to change it's pointers to some other D.