code: def has_var_groups(self):
          '''Returns a set of the variant group ids that this cluster has'''
          ids = set()
          for d in self.data:
              if self._has_known_variant(d) != 'no' and d['var_group'] != '.':
                  ids.add(d['var_group'])
          return idf has_var_groups(self):
          '''Returns a set of the variant group ids that this cluster has'''
          ids = set()
          for d in self.data:
              if self._has_known_variant(d) != 'no' and d['var_group'] != '.':
                  ids.add(d['var_group'])
          return ids
docs: Returns a set of the variant group ids that this cluster has