def METHOD_NAME(self):
    obj = Configuration()
    obj.merge({
        "execution": [{
            "executor": "jmeter",
            "iterations": 10,
        }, {
            "executor": "selenium",
            "iterations": 30,
        }],
    })
    obj.merge({
        "$execution": [{"iterations": 20}],
    })
    self.assertEqual(obj["execution"][0]["iterations"], 20)
    self.assertEqual(obj["execution"][1]["iterations"], 30)