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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 head(self, n=None, **kwargs):
 """ Return the first n rows. Execute at once. :param n: :return: result frame :rtype: :class:`odps.df.backends.frame.ResultFrame` """

        if n is None:
            n = options.display.max_rows
        return self._handle_delay_call('execute', self, head=n, **kwargs)