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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 refresh(self):
 """Refresh the server and it's child objects. This method removes all the cache information in the server and it's child objects, and fetches the information again from the server using hpssacli/ssacli command. :raises: HPSSAOperationError, if hpssacli/ssacli operation failed. """

        config = self._get_all_details()

        raid_info = _convert_to_dict(config)
        self.controllers = []

        for key, value in raid_info.items():
            self.controllers.append(Controller(key, value, self))

        self.last_updated = time.time()