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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 get_report_overview(self, month, file_path):
 """Downloads a report overview :param month: month as datetime instance, or string in YYYY-MM format :type month: str or datetime :param str file_path: location to store output file :return: outcome :rtype: True or None """

        api = self._get_api(billing.DefaultApi)
        month = self._month_converter(month)
        response = api.get_billing_report(month=month)
        if file_path and response:
            content = api.api_client.sanitize_for_serialization(response.to_dict())
            with open(file_path, 'w') as fh:
                fh.write(
                    json.dumps(
                        content,
                        sort_keys=True,
                        indent=2,
                    )
                )
        return response