def _hasattrs(self, expr, attrs):
        for attr in attrs:
            if not hasattr(expr, attr):
                return False

        return True
Regression test for #13071: NullBooleanField should not throw
dataset/ETHPy150Open sympy/sympy/sympy/simplify/epathtools.py/EPath._hasattrs--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/tests/regressiontests/model_fields/tests.py/BasicFieldTests.test_nullbooleanfield_blank