code: def get_evcodes_all(self, inc_set=None, exc_set=None):
          
          codes = self._get_grps_n_codes(inc_set) if inc_set else set(self.code2nt)
          if exc_set:
              codes.difference_update(self._get_grps_n_codes(exc_set))
          return codes
docs: Get set of evidence codes given include set and exclude set