How to drop selected borrows when converting a struct via trait to another, all called from a wrapper function?

I'm sorry if the title is unclear - I couldn't figure a better one. Also my apologies for my English or if my terminology isn't exact, I'm not a native speaker (open to any feedback.) TL;DR: Here's reproducible example in the playground.. The problem A context value has the make_scope method which receives an input value. The input value implements the Begin trait which begin method consumes it and returns end value which implements the End trait. When the new end value is created, some of ...