Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/IOFactory.php
public static function createReader($readerType)
    {
        if (!isset(self::$readers[$readerType])) {
            throw new Reader\Exception("No reader found for type $readerType");
        }

        // Instantiate reader
        $className = self::$readers[$readerType];
        $reader = new $className();

        return $reader;
    }
public static function createReader($readerType)
    {
        if (!isset(self::$readers[$readerType])) {
            throw new Reader\Exception("No reader found for type $readerType");
        }

        // Instantiate reader
        $className = self::$readers[$readerType];
        $reader = new $className();

        return $reader;
    }
Create Reader\IReader.

@param string $readerType Example: Xlsx

@throws Reader\Exception

@return Reader\IReader