Parses a super range.
         SuperRange ::= Range | Join | Complement

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))