Function noid_check_digit 

pub fn noid_check_digit<S>(value: S) -> Option<char>
where
    S: AsRef<str>,

Calculate check xdigit (“extended digit”) IAW NOID check digit algorithm (NCDA)

Notes

• Check digits are not expected to cover qualifiers
• If check digit is present in an ARK, by convention it is the right-most character of the so called “check zone”
• The “check zone” is composed of the NAAN and assigned name, separated by a forward slash
• Forward slashes do not contribute to the check digit sum, but do impact the character position index
• NCDA is guaranteed against single-character errors
• NCDA is guaranteed against transposition of two single characters

References

• https://github.com/internetarchive/arklet
• https://github.com/no-reply/pynoid