src/Blocks/BlockCode.php
public function validateLineType($lineNumber)
    {
        $dataObject = $this->factory->getDataObject();
        $lineContent = $dataObject->getLine($lineNumber);

        $charactersCounter = count_chars($lineContent, 1);
        if (!isset($charactersCounter[static::BACKTICK_CODE]) || $charactersCounter[static::BACKTICK_CODE] !== 3) {
            return false;
        }

        return (bool) preg_match('/^([\`]{3})/', $lineContent);
    }
public function validateLineType($lineNumber)
    {
        $dataObject = $this->factory->getDataObject();
        $lineContent = $dataObject->getLine($lineNumber);

        $charactersCounter = count_chars($lineContent, 1);
        if (!isset($charactersCounter[static::BACKTICK_CODE]) || $charactersCounter[static::BACKTICK_CODE] !== 3) {
            return false;
        }

        return (bool) preg_match('/^([\`]{3})/', $lineContent);
    }
@param int $lineNumber

@return bool