def get_closest_cities(self, kms):
    cities = []
allcities = self.country.city_set
for city in allcities:
    distance = HaversineDistance((self.location.lat, self.location.lon), (
        city.location.lat, city.location.lon))
if not distance >= kms:
    cities.append((city.name, int(distance)))
Рассчитайте расстояние между городами и найдите близлежащие города на основе GeoPT в Python на Google App Engine.