}
// We can convert any vector of digits into a number, by removing trailing zeros. The `mut`
- // declaration for `v` here is just like the one in `let mut ...`, it says that we will locally
- // change the vector `v`.
+ // declaration for `v` here is just like the one in `let mut ...`: We completely own `v`, but Rust
+ // still asks us to make our intention of modifying it explicit. This `mut` is *not* part of the
+ // type of `from_vec` - the caller has to give up ownership of `v` anyway, so they don't care anymore
+ // what you do to it.
//
// **Exercise 05.1**: Implement this function.
//