public function findSequence(array $sequence, $start = 0, $end = null, $caseSensitive = true)
    {
        $sequenceCount = \count($sequence);
        if (0 === $sequenceCount) {
            throw new \InvalidArgumentException('Invalid sequence.');
        }

        // $end defaults to the end of the collection
        $end = null === $end ? \count($this) - 1 : min($end, \count($this) - 1);

        if ($start + $sequenceCount - 1 > $end) {
            return null;
        }

        // make sure the sequence content is "meaningful"
        foreach ($sequence as $key => $token) {
            // if not a Token instance already, we convert it to verify the meaningfulness
            if (!$token instanceof Token) {
                if (\is_array($token) && !isset($token[1])) {
                    // fake some content as it is required by the Token constructor,
                    // although optional for search purposes
                    $token[1] = 'DUMMY';
                }
                $token = new Token($token);
            }

            if ($token->isWhitespace() || $token->isComment() || '' === $token->getContent()) {
                throw new \InvalidArgumentException(sprintf('Non-meaningful token at position: %s.', $key));
            }
        }

        if (!self::isLegacyMode()) {
            foreach ($sequence as $token) {
                if (!$this->isTokenKindFound($this->extractTokenKind($token))) {
                    return null;
                }
            }
        }

        // remove the first token from the sequence, so we can freely iterate through the sequence after a match to
        // the first one is found
        $key = key($sequence);
        $firstCs = Token::isKeyCaseSensitive($caseSensitive, $key);
        $firstToken = $sequence[$key];
        unset($sequence[$key]);

        // begin searching for the first token in the sequence (start included)
        $index = $start - 1;
        while (null !== $index && $index <= $end) {
            $index = $this->getNextTokenOfKind($index, [$firstToken], $firstCs);

            // ensure we found a match and didn't get past the end index
            if (null === $index || $index > $end) {
                return null;
            }

            // initialise the result array with the current index
            $result = [$index => $this[$index]];

            // advance cursor to the current position
            $currIdx = $index;

            // iterate through the remaining tokens in the sequence
            foreach ($sequence as $key => $token) {
                $currIdx = $this->getNextMeaningfulToken($currIdx);

                // ensure we didn't go too far
                if (null === $currIdx || $currIdx > $end) {
                    return null;
                }

                if (!$this[$currIdx]->equals($token, Token::isKeyCaseSensitive($caseSensitive, $key))) {
                    // not a match, restart the outer loop
                    continue 2;
                }

                // append index to the result array
                $result[$currIdx] = $this[$currIdx];
            }

            // do we have a complete match?
            // hint: $result is bigger than $sequence since the first token has been removed from the latter
            if (\count($sequence) < \count($result)) {
                return $result;
            }
        }
    }