mod inner {
    mod types {
        pub struct Key;
    }

    mod interface {
        use crate::inner::types::Key;

        pub trait GetIF {
            fn get(&self, key: Key);
        }
    }

    pub use interface::GetIF;
}

use crate::inner::GetIF;
use crate::inner::types::Key;

struct Foobar;

impl GetIF for Foobar {
    fn get(&self, key: Key) {}
}