<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get(self, sensor_type='temperature_core'):
 """Get sensors list."""

        self.__update__()
        if sensor_type == 'temperature_core':
            ret = [s for s in self.sensors_list if s['unit'] == SENSOR_TEMP_UNIT]
        elif sensor_type == 'fan_speed':
            ret = [s for s in self.sensors_list if s['unit'] == SENSOR_FAN_UNIT]
        else:
            # Unknown type
            logger.debug("Unknown sensor type %s" % sensor_type)
            ret = []
        return ret