A position on the planet Earth is specified by latitude and longitude (in degrees). The distance between two points on a sphere can be calculated with the following formula, where latitude and longitude are in radians and r is the radius of the sphere:

distance = r * arccos(sin(latitude1) * sin(latitude2) + cos(latitude1) * cos(latitude2) * cos(longitude1 - longitude2))

The radius of the planet Earth is 6371 km

Your task is to compute the distance between two Location objects.