Set the main dataframe instance to rows that do not
        contains a string value in a column

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