return (lat,lon) for the grid coordinates

def latlon(self):
        '''return (lat,lon) for the grid coordinates'''
        from MAVProxy.modules.lib.ANUGA import lat_long_UTM_conversion
        (lat, lon) = lat_long_UTM_conversion.UTMtoLL(self.northing, self.easting, self.zone, isSouthernHemisphere=(self.hemisphere=='S'))
        return (lat, lon)