def test_identity(self):
        self.flakes('''
        x = 10
        y = 20
        x is y
        x is not y
        ''')
__setitem__ is overloaded to access the underlying numpy values with
dataset/ETHPy150Open kevinw/pyflakes/pyflakes/test/test_other.py/Test.test_identity--crossover with--dataset/ETHPy150Open pydata/xarray/xarray/core/variable.py/Variable.__setitem__