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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 update_pointed(self):
        '''
        Grabs the latest file contents based on the pointer uri
        '''
        # only grab file if our pointer is still good (not None)
        if not self.pointed_at_expired:
            try:
                conf_string, stat2 = self.zoo_client.get(self.point_path,
                                                    watch=self.watch_pointed)
            except ZookeeperError:
                self.old_data = ''
                self.set_valid(False)
                self.pointed_at_expired = True
                self.call_error(self.INVALID_PATH)
                return

            if self.compare_data(conf_string):
                self.call_config(conf_string)
            self.set_valid(True)