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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 mfw_(self, col, sw_lang="english", limit=100):
 """ Returns a Dataswim instance with the most frequent words in a column exluding the most common stop words """

        df = self._mfw(col, sw_lang, limit)
        if df is None:
            self.err("Can not find most frequent words")
            return
        return self._duplicate_(df)