pub fn normalize_user_code(input: &str) -> Option<String>Expand description
Formats eight characters of USER_CODE_ALPHABET the way they are
shown: WDJB-MJHT.
Reads what a person typed, too: case, the hyphen, spaces and any other
character outside the alphabet are ignored, as RFC 8628 ยง6.1 suggests,
so wdjb mjht is the same code. None unless exactly eight remain.