Print GO namedtuples in their sections.

def prt_info(self, prt, sections=None):
        """Print GO namedtuples in their sections."""
        if sections is None:
            sections = self.grprobj.get_sections_2d()
        num_goids = 0
        for section_name, nts_flat in sections:
            num_nts = len(nts_flat)
            num_goids += num_nts
            prt.write("{N:3} GO IDs in section({SEC})\n".format(N=num_nts, SEC=section_name))
        prt.write("{N:3} GO IDs\n".format(N=num_goids))