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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 prune_by_ngram_size(self, minimum=None, maximum=None):
 """Removes results rows whose n-gram size is outside the range specified by `minimum` and `maximum`. :param minimum: minimum n-gram size :type minimum: `int` :param maximum: maximum n-gram size :type maximum: `int` """

        self._logger.info('Pruning results by n-gram size')
        if minimum:
            self._matches = self._matches[
                self._matches[constants.SIZE_FIELDNAME] >= minimum]
        if maximum:
            self._matches = self._matches[
                self._matches[constants.SIZE_FIELDNAME] <= maximum]