@property
    def null_srid(self):
        info = geos_version_info()
        if info['version'] == '3.0.0' and info['release_candidate']:
            return -1
        else:
            return None
Returns the proper null SRID depending on the GEOS version.
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.4/django/contrib/gis/geos/tests/test_geos.py/GEOSTest.null_srid