use std::io;

pub trait Backend
where
    Self: Sized,
{
    type Write: for<'a> io::Write;

    fn as_io(&mut self) -> Self::Write;
}

impl<T> Backend for T {
    type Write = &mut T;

    fn as_io(&mut self) -> &mut T {
        self
    }
}

fn main() {

}