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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 start_change(self, direction):
 """Start changing light level manually. Direction should be 'up' or 'down'"""

        self.logger.info("Dimmer %s start_change: %s", self.device_id, direction)

        if direction == 'up':
            level = '01'
        elif direction == 'down':
            level = '00'
        else:
            self.logger.error("Dimmer %s start_change: %s is invalid, use up or down",
                              self.device_id, direction)
            return False

        self.hub.direct_command(self.device_id, '17', level)
        success = self.hub.check_success(self.device_id, '17',
                                         self.hub.brightness_to_hex(level))
        if success:
            self.logger.info("Dimmer %s start_change: Light started changing successfully",
                             self.device_id)
            self.hub.clear_device_command_cache(self.device_id)
        else:
            self.logger.error("Dimmer %s start_change: Light did not change",
                              self.device_id)

        return success