def add_mrjob_to_pythonpath(self):
        os.environ['PYTHONPATH'] = (
            mrjob_pythonpath() + ':' + os.environ.get('PYTHONPATH', ''))
call this for tests that are going to invoke a subprocess
dataset/ETHPy150Open Yelp/mrjob/tests/sandbox.py/SandboxedTestCase.add_mrjob_to_pythonpath