It is just one considerably less implicit rule that you have to internalize ahead of knowledge OOP. Other languages pick syntactic sugar more than semantic simplicity, python is not other languages. Evan Plaice If img-src 'self' facts: is just not working for yourself simply because you manipulate picture with JavaScript, https://self-adhesive-mini-trunki57899.ageeksblog.com/36166342/5-easy-facts-about-accessory-boxes-described