1. `hash.Sum([]byte{})` does _not_ do what I expected it to do. It prefixes the _output_ with those bytes. I expected it to use it as a suffix for the hashing algorithm, but without actually affecting the underlying hash data.
i.e. hash.Sum([]byte("foobar") -> "foobar<hash(written bytes)>" instead of "<hash(written bytes + "foobar">"