https://eduschool40.blog/%d8%a7%d9%84%d8%ac%d9%85%d9%84%d8%a9-%d8%a7%d9%84%d8%ba%d8%b1%d8%b6%d9%8a%d8%a9-purpose-clause-%d9%81%d9%8a-%d8%a7%d9%84%d9%84%d8%ba%d8%a9-%d8%a7%d9%84%d8%a7%d9%86%d8%ac%d9%84%d9%8a%ef%bf%bd%ef%bf%bd/