Method error

cranelift/isle/isle/src/parser.rs:55–60

(&self, pos: Pos, msg: String)

    }

    fn error(&self, pos: Pos, msg: String) -> Error {
        Error::ParseError {
            msg,
            span: Span::new_single(pos),
        }
    }

    fn expect<F: Fn(&Token) -> bool>(&mut self, f: F) -> Result<Token> {
        if let Some(&(pos, ref peek)) = self.lexer.peek() {