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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 _sent_without_response(self, send_time_before):
 """Used internally to determine whether the request has not received any response from the container and was send before the given time. Unsent requests are not considered."""

        return not self._messages and self._send_time and self._send_time < send_time_before