use std::fmt; pub enum RogError { ParseFanLevel, NotSupported, } impl fmt::Display for RogError { // This trait requires `fmt` with this exact signature. fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match self { RogError::ParseFanLevel => write!(f, "Parse error"), RogError::NotSupported => write!(f, "Not supported"), } } }