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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 alter(self, operation, timeout=None, metadata=None, credentials=None):
 """Runs a modification via this client."""

        new_metadata = self.add_login_metadata(metadata)

        try:
            return self.any_client().alter(operation, timeout=timeout,
                                           metadata=new_metadata,
                                           credentials=credentials)
        except Exception as error:
            if util.is_jwt_expired(error):
                self.retry_login()
                new_metadata = self.add_login_metadata(metadata)
                return self.any_client().alter(operation, timeout=timeout,
                                               metadata=new_metadata,
                                               credentials=credentials)
            else:
                raise error