nestedNot example

throw SyntaxErrorException::notAtTheStartOfASelector('scope');
                        }
                    }
                    continue;
                }

                $stream->getNext();
                $stream->skipWhitespace();

                if ('not' === strtolower($identifier)) {
                    if ($insideNegation) {
                        throw SyntaxErrorException::nestedNot();
                    }

                    [$argument, $argumentPseudoElement] = $this->parseSimpleSelector($stream, true);
                    $next = $stream->getNext();

                    if (null !== $argumentPseudoElement) {
                        throw SyntaxErrorException::pseudoElementFound($argumentPseudoElement, 'inside ::not()');
                    }

                    if (!$next->isDelimiter([')'])) {
                        throw SyntaxErrorException::unexpectedToken('")"', $next);
                    }