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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 serve_forever(self, poll_interval=0.5):
 """ Wait for incomming requests. """

        self.serial_port.timeout = poll_interval

        while not self._shutdown_request:
            try:
                self.serve_once()
            except (CRCError, struct.error) as e:
                log.error('Can\'t handle request: {0}'.format(e))
            except (SerialTimeoutException, ValueError):
                pass