Function cloned 

pub fn cloned<T>(a: T, b: T) -> bool
where
    T: Clone,

Predicate indicating b is “a clone” of a; i.e., b could be the result of calling a.clone() or is equal to a.

By always considering a value to be a clone of itself, regardless of the definition of T::clone, this definition is useful in places where ‘clone’ calls might be optimized to copies. This is particularly common in the Rust stdlib.