protected function find($functionNameToSearch, Tokens $tokens, $start = 0, $end = null)
    {
        // make interface consistent with findSequence
        $end = null === $end ? $tokens->count() : $end;

        // find raw sequence which we can analyse for context
        $candidateSequence = [[T_STRING, $functionNameToSearch], '('];
        $matches = $tokens->findSequence($candidateSequence, $start, $end, false);
        if (null === $matches) {
            // not found, simply return without further attempts
            return null;
        }

        // translate results for humans
        list($functionName, $openParenthesis) = array_keys($matches);

        $functionsAnalyzer = new FunctionsAnalyzer();

        if (!$functionsAnalyzer->isGlobalFunctionCall($tokens, $functionName)) {
            return $this->find($functionNameToSearch, $tokens, $openParenthesis, $end);
        }

        return [$functionName, $openParenthesis, $tokens->findBlockEnd(Tokens::BLOCK_TYPE_PARENTHESIS_BRACE, $openParenthesis)];
    }