trait GetIterator<'a> {
    type Item;
    type IntoIter: Iterator<Item=Self::Item>;

    fn iter(&'a self) -> Self::IntoIter;
}

// impl<'a, I: 'a> GetIterator<'a> for I where I: Iterator + Clone {
//     type Item = I::Item;
//     type IntoIter = I;

//     fn iter(&'a self) -> Self::IntoIter {
//         self.clone()
//     }
// }

impl<'a, T: 'a> GetIterator<'a> for T where &'a T: IntoIterator {
    type Item = <&'a T as IntoIterator>::Item;
    type IntoIter = <&'a T as IntoIterator>::IntoIter;

    fn iter(&'a self) -> Self::IntoIter {
        self.into_iter()
    }
}

fn main() {
    // let x: Vec<u32> = Vec::new();
    // GetIterator::iter(&x);
}