def value_to_string(self, value):
        return unicode(value).lower()
is_eager should return False if not set for specified backend.
dataset/ETHPy150Open jahlborn/appengine-rest-server/src/main/python/rest/__init__.py/BooleanHandler.value_to_string--crossover with--dataset/ETHPy150Open rapidsms/rapidsms/rapidsms/router/celery/tests.py/CeleryRouterConfigTest.test_eager_not_set