code: def get_nearest_site(sites, lat, lon):
      
      for site in sites:
          site.distance_to_coords(lat, lon)
      sites.sort(key=operator.attrgetter("distance"))
      return sites[0].ident
docs: Return a string which can be used as "request" in calls to loc_forecast
      and loc_observations.
      
      sites:    List of Site instances
      lat:      float or int.  Interesting latitude
      lon:      float or int.  Interesting longitude