pub trait Class {
// Provided methods
fn base(&self) -> &'static str { ... }
fn color(&self) -> Option<&'static str> { ... }
fn size(&self) -> Option<&'static str> { ... }
fn variant(&self) -> Option<&'static str> { ... }
fn animation(&self) -> Option<&'static str> { ... }
fn orientation(&self) -> Option<&'static str> { ... }
fn side(&self) -> Option<&'static str> { ... }
}