findClosest method
Finds the GeoLocationNode (City, Region, or Country) instance closest to the provided target
Returns: A City when possible, otherwise a Region or a Country, whichever is more specific.
Implementation
GeoLocationNode? findClosest(GeoCoords target) {
var region = states.findClosestTo(target);
if (region == null) return this;
return region.findClosestCity(target) ?? region;
}