Function compositionLocalOfWithPolicy 

pub fn compositionLocalOfWithPolicy<T: Clone + 'static>(
    default: impl Fn() -> T + 'static,
    equivalent: impl Fn(&T, &T) -> bool + Send + Sync + 'static,
) -> CompositionLocal<T>

Creates a CompositionLocal whose default is made by default. A provided value replaces the previous one only when equivalent returns false for the two.