code: def get_closest_stop(self, lat, lon):
          
          cur = self.conn.cursor()
          min_dist = float("inf")
          min_stop_I = None
          rows = cur.execute("SELECT stop_I, lat, lon FROM stops")
          for stop_I, lat_s, lon_s in rows:
              dist_now = wgs84_distance(lat, lon, lat_s, lon_s)
              if dist_now < min_dist:
                  min_dist = dist_now
                  min_stop_I = stop_I
          return min_stop_I
docs: Get closest stop to a given location.
  
          Parameters
          ----------
          lat: float
              latitude coordinate of the location
          lon: float
              longitude coordinate of the location
  
          Returns
          -------
          stop_I: int
              the index of the stop in the database