code: def _get_fout_go(self):
          
          assert self.goids, "NO VALID GO IDs WERE PROVIDED AS STARTING POINTS FOR HIERARCHY REPORT"
          base = next(iter(self.goids)).replace(':', '')
          upstr = '_up' if 'up' in self.kws else ''
          return "hier_{BASE}{UP}.{EXT}".format(BASE=base, UP=upstr, EXT='txt')
docs: Get the name of an output file based on the top GO term.