docs: def _parse_nested_interval(self, tokens):
          """ Parses a super range.
           SuperRange ::= Range | Join | Complement
          """
          if tokens[0].isdigit():
              return self._parse_interval(tokens)
          elif tokens[0] in ['join', 'order']:
              return self._parse_join(tokens)
          elif tokens[0] == 'complement':
              return self._parse_complement(tokens)
          raise ValueError('interval {} does not fit pattern.'.format(tokens))