// This file is part of ICU4X. For terms of use, please see the file
// called LICENSE at the top level of the ICU4X source tree
// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
impl_tinystr_subtag!(/// A key used in a list of [`Keywords`](super::Keywords).
////// The key has to be a two ASCII alphanumerical characters long, with the first
/// character being alphanumeric, and the second being alphabetic.
///////// # Examples
////// ```
/// use icu::locid::extensions::unicode::Key;
////// assert!("ca".parse::<Key>().is_ok());
/// ```
Key,extensions::unicode::Key,
extensions_unicode_key,2..=2,
s,
s.all_bytes()[0].is_ascii_alphanumeric()&& s.all_bytes()[1].is_ascii_alphabetic(),
s.to_ascii_lowercase(),(s.all_bytes()[0].is_ascii_lowercase()|| s.all_bytes()[0].is_ascii_digit())&& s.all_bytes()[1].is_ascii_lowercase(),
InvalidExtension,["ca","8a"],["a","a8","abc"],);