Comment 4 for bug 1821093

Just a note that, when implemented, libraries must be able to enable or disable the CAPTCHA on this form (maybe through a library setting). CAPTCHAs have serious, intrinsic accessibility issues: https://www.w3.org/TR/turingtest/#the-accessibility-challenge

WebAIM has a list of anti-spam techniques without so many accessibility drawbacks: https://webaim.org/blog/spam_free_accessible_forms/ -- maybe some of these could be useful too.