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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 flush_and_refresh(self, index):
 """Flush and refresh one or more indices. .. warning:: Do not call this method unless you know what you are doing. This method is only intended to be called during tests. """

        self.client.indices.flush(wait_if_ongoing=True, index=index)
        self.client.indices.refresh(index=index)
        self.client.cluster.health(
            wait_for_status='yellow', request_timeout=30)
        return True