Function kp_box 

pub fn kp_box<'a, T>() -> KpType<'a, Box<T>, T>

Create a keypath for unwrapping Box -> T

Example

use rust_key_paths::kp_box;
let boxed = Box::new("value".to_string());
let kp = kp_box();
assert_eq!(kp.get(&boxed), Some(&"value".to_string()));