Seems weird to jump through hoops to keep an outdated JavaScript library with a custom prototype working. When you create custom prototypes this is the risk you

Seems weird to jump through hoops to keep an outdated JavaScript library with a custom prototype working. When you create custom prototypes this is the risk you take. Name your prototypes accordingly, so they are unlikely to clash anything. As an example mtflatten, or _flatten (like underscore.js and other libraries).