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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_arn_from_idempotency_token(self, token):
 """ If token doesnt exist, return None, later it will be set with an expiry and arn. If token expiry has passed, delete entry and return None Else return ARN :param token: String token :return: None or ARN """

        now = datetime.datetime.now()
        if token in self._idempotency_tokens:
            if self._idempotency_tokens[token]['expires'] < now:
                # Token has expired, new request
                del self._idempotency_tokens[token]
                return None
            else:
                return self._idempotency_tokens[token]['arn']

        return None