pub trait ApiCodeTransform {
// Required method
fn transform(&self, code: &str) -> Result<String>;
// Provided methods
fn transforms(&self, codes: &[String]) -> Result<Vec<String>> { ... }
fn sz_transform(&self, _code: &str) -> Result<String> { ... }
fn sh_transform(&self, _code: &str) -> Result<String> { ... }
fn hk_transform(&self, _code: &str) -> Result<String> { ... }
fn us_transform(&self, _code: &str) -> Result<String> { ... }
}