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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 ncontains(self, column, value):
 """ Set the main dataframe instance to rows that do not contains a string value in a column """

        df = self.df[self.df[column].str.contains(value) == False]
        if df is None:
            self.err("Can not select contained data")
            return
        self.df = df