Method constructor

docs/app/js/sanddance-app.js:110700–110711

(values, key = keyof)

}
class InternSet extends Set {
    constructor(values, key = keyof){
        super();
        Object.defineProperties(this, {
            _intern: {
                value: new Map()
            },
            _key: {
                value: key
            }
        });
        if (values != null) for (const value of values)this.add(value);
    }
    has(value) {
        return super.has(intern_get(this, value));
    }