// **Exercise 07.1**: Add some more testcases. In particular, make sure you test the behavior of
// `vec_min` on an empty vector. Also add tests for `BigInt::from_vec` (in particular, removing
// trailing zeros). Finally, break one of your functions in a subtle way and watch the test fail.
-//
// **Exercise 07.2**: Go back to your good ol' `SomethingOrNothing`, and implement `Display` for it.
// (This will, of course, need a `Display` bound on `T`.) Then you should be able to use them with