docs: def _parse_complement(self, tokens):
          """ Parses a complement
           Complement ::= 'complement' '(' SuperRange ')'
          """
          tokens.pop(0)  # Pop 'complement'
          tokens.pop(0)  # Pop '('
          res = self._parse_nested_interval(tokens)
          tokens.pop(0)  # Pop ')'
          res.switch_strand()
          return res