Write to outfiles.

def prt_outfiles_grouped(self, outfiles):
        """Write to outfiles."""
        for outfile in outfiles:
            if outfile.endswith(".xlsx"):
                self.wr_xlsx(outfile)
            elif outfile.endswith(".txt"):
                self.wr_txt(outfile)
            else:
                self.wr_tsv(outfile)