Function rhumb_azimuth_with 

pub fn rhumb_azimuth_with<P1, P2, S>(
    first: &P1,
    second: &P2,
    strategy: S,
) -> S::Out
where
    P1: Point,
    P2: Point,
    S: AzimuthStrategy<P1, P2>,

Constant compass bearing using an explicit rhumb strategy.