def close(self, graceful=True):
    raise NotImplementedError()
This tests that echo may be toggled off.
dataset/ETHPy150Open google/anvil-build/anvil/task.py/TaskExecutor.close--crossover with--dataset/ETHPy150Open Calysto/metakernel/metakernel/tests/test_expect.py/ExpectTestCase.test_expect_setecho_off