def concat(self, *dss, **kwargs):
        """
        Concatenate dataswim instances from and
                set it to the main dataframe

        :param dss: dataswim instances to concatenate
        :type dss: Ds
        :param kwargs: keyword arguments for ``pd.concat``


        """
        try:
            df = pd.DataFrame()
            for dsx in dss:
                df = pd.concat([df, dsx.df], **kwargs)
            self.df = df
        except Exception as e:
            self.err(e, "Can not concatenate data")