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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 setup_sensors(self):
 """Setup some server sensors."""

        self._add_result = Sensor.float("add.result",
            "Last ?add result.", "", [-10000, 10000])
        self._add_result.set_value(0, Sensor.UNREACHABLE)

        self._time_result = Sensor.timestamp("time.result",
            "Last ?time result.", "")
        self._time_result.set_value(0, Sensor.INACTIVE)

        self._eval_result = Sensor.string("eval.result",
            "Last ?eval result.", "")
        self._eval_result.set_value('', Sensor.UNKNOWN)

        self._fruit_result = Sensor.discrete("fruit.result",
            "Last ?pick-fruit result.", "", self.FRUIT)
        self._fruit_result.set_value('apple', Sensor.ERROR)

        self.add_sensor(self._add_result)
        self.add_sensor(self._time_result)
        self.add_sensor(self._eval_result)
        self.add_sensor(self._fruit_result)