Code shared from the Rust Playground

playground.rs

use std::io::Read;
use std::io::Cursor;
    
struct B(String);
struct RefPairA<'b>(&'b B, String);

trait GetPair {
    fn pair(&self) -> (&str, &str);
}

impl<'b> GetPair for RefPairA<'b> {
    fn pair(&self) -> (&'b str, &str) {
        (&self.0.0, &self.1)
    }
}

fn get_data_a(p: &RefPairA) -> impl Read {
    let (b, s) = p.pair();
    Cursor::new(format!("{}/{}", b, s).into_bytes())
}

fn get_data(p: &impl GetPair) -> impl Read {
    let (b, s) = p.pair();
    Cursor::new(format!("{}/{}", b, s).into_bytes())
}

fn data_a() -> impl Read {
    let b = B("foo".to_owned());
    let a = RefPairA(&b, "bar".to_owned());
    get_data_a(&a)
}

fn data() -> impl Read {
    let b = B("foo".to_owned());
    let a = RefPairA(&b, "bar".to_owned());
    get_data(&a)
}