Method constructor

external/.d3.js:431–435

(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));
  }