pub trait ToColorRep {
type ColorRGBA;
type ColorHSLA;
type ColorRGBAByte;
// Required methods
fn to_rgba_coef(&self) -> Self::ColorRGBA;
fn to_hsla(&self) -> Self::ColorHSLA;
fn to_rgba_u8(&self) -> Self::ColorRGBAByte;
// Provided method
fn to_color(&self) -> Self::ColorRGBA { ... }
}