Return the print fields in the go2nt namedtuple.

def __init_prt_flds(self):
        """Return the print fields in the go2nt namedtuple."""
        prt_flds = ['NS', 'level', 'depth']
        if self.relationships:
            prt_flds.append('reldepth')
        prt_flds.extend(['GO', 'alt', 'GO_name'])
        if 'dcnt' in self.kw_elems:
            prt_flds.append('dcnt')
        if 'D1' in self.kw_elems:
            prt_flds.append('D1')
        if 'tcnt' in self.kw_elems:
            prt_flds.append('tcnt')
            prt_flds.append('tfreq')
            prt_flds.append('tinfo')
        if self.relationships:
            prt_flds.append('childcnt')
            prt_flds.append('REL')
            prt_flds.append('REL_short')
            prt_flds.append('rel')
        prt_flds.append('id')
        return prt_flds