trait Console {
    fn print_str(&mut self, text: &str);
}

trait ConsoleExt: Console {
    fn print<T: AsRef<str>>(&mut self, text: T) {
        self.print_str(text.as_ref())
    }
}

impl<T> ConsoleExt for T where T: ?Sized + Console {}

struct RootConsole;

impl Console for RootConsole {
    fn print_str(&mut self, text: &str) {
        unimplemented!()
    }
}

fn main() {
    let mut console = RootConsole;
    console.print("hello!");
}