lib/index.esm.js
function (key) {
        if (!_isObject(key)) return false;
        var data = getWeak(key);
        if (data === true) return uncaughtFrozenStore(_validateCollection(this, NAME))['delete'](key);
        return data && _has(data, this._i) && delete data[this._i];
      }
function (key) {
        if (!_isObject(key)) return false;
        var data = getWeak(key);
        if (data === true) return uncaughtFrozenStore(_validateCollection(this, NAME))['delete'](key);
        return data && _has(data, this._i) && delete data[this._i];
      }
23.3.3.2 WeakMap.prototype.delete(key) 23.4.3.3 WeakSet.prototype.delete(value)