code: def _get_prtflds(self):
          
          # User-specified print fields
          ntflds = self.gosubdag.prt_attr['flds']
          prt_flds = self.kws.get('prt_flds')
          if prt_flds:
              return prt_flds.intersection(ntflds)
          exclude = set()
          # Default print fields
          if self.gosubdag.relationships:
              exclude.add('level')
          return set(f for f in ntflds if f not in exclude)
docs: Get print fields for GO header.