trait A {
    fn get_a(&self) -> u32;
}

trait B<'a, 'b> {
    fn get_b(&'a self) -> &'b u32;
}

trait Common<'a, T> {
    fn get(&'a self) -> T;
}

struct SA {
    val : u32
}

impl A for SA {
    fn get_a(&self) -> u32 {
        self.val
    }
}

struct SB<'b> {
    val : &'b u32
}

impl<'a, 'b> B<'a, 'b> for SB<'b> {
    fn get_b(&'a self) -> &'b u32 {
        self.val
    }
}

impl<'a, T> Common<'a, u32> for T where T: A {
    fn get(&'a self) -> u32 {
        self.get_a()
    }
}

impl<'a, 'b, T> Common<'a, &'b u32> for T where T: B<'a, 'b> {
    fn get(&'a self) -> &'b u32 {
        self.get_b()
    }
}

fn main() {
    let a = SA { val: 42 };
    let b = SB { val: &13 };

    println!("{}", a.get());
    println!("{}", b.get());
}