**Update:**
Since publishing this post, I have written [another]({% post_url 2018-11-16-stacked-borrows-implementation %}) blog post about a slightly adjusted version of Stacked Borrows (the first version that actually got implemented).
That other post is self-contained, so if you are just interested in the current state of Stacked Borrows, I suggest you go there.
+Only go on reading here if you want some additional historic context.
**/Update**
## 1 Validity-based vs. Access-based