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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def post(self, url: str, data: str, expected_status_code=201):
 """ Do a POST request """

        r = requests.post(self._format_url(url), json=data, headers=self.headers, timeout=TIMEOUT)
        self._check_response(r, expected_status_code)

        return r.json()