pub(crate) trait PunycodeCodeUnit {
    // Required methods
    fn is_delimiter(&self) -> bool;
    fn is_ascii(&self) -> bool;
    fn digit(&self) -> Option<u32>;
    fn char(&self) -> char;
    fn char_ascii_lower_case(&self) -> char;
}pub(crate) trait PunycodeCodeUnit {
    // Required methods
    fn is_delimiter(&self) -> bool;
    fn is_ascii(&self) -> bool;
    fn digit(&self) -> Option<u32>;
    fn char(&self) -> char;
    fn char_ascii_lower_case(&self) -> char;
}