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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 fetch_transaction_status(self, transaction_id):
 """ Get the transaction current status. :param transaction_id: :return: """

        url = "%s%s%s/status" % (self.api_endpoint, constants.TRANSACTION_STATUS_ENDPOINT, transaction_id)

        username = self.base.get_username()
        password = self.base.get_password(username=username, request_url=url)

        response = requests.get(url, auth=HTTPBasicAuth(username=username, password=password))

        if response.status_code == 404:
            raise TransactionDoesNotExist('Wrong transaction ID!')

        if not self.base.verify_response(response.json()):
            raise SignatureValidationException('Server signature verification has failed')

        return response.json()