@classmethod
    def factory(cls, global_conf, **local_conf):
        return cls
should provide a way to change file field value
dataset/ETHPy150Open openstack/oslo.middleware/oslo_middleware/base.py/Middleware.factory--crossover with--dataset/ETHPy150Open cobrateam/splinter/tests/test_webdriver_chrome.py/ChromeBrowserTest.test_attach_file