I regularly add Symbol based features to JS libraries I'm using (named methods are riskier, of course)
import { SomeStreamClass as SomeStreamClass_ } from "some/library"
export class SomeStreamClass extends SomeStreamClass_ {
[someSymbol] (...) { ... }
...
}
I have not blown my foot off yet with this approach but, uh, no warranty, express or implied.It's been working excellently for me so far though.