code: function forEach(callbackfn /* , that = undefined */) {
  	        _validateCollection(this, NAME);
  	        var f = _ctx(callbackfn, arguments.length > 1 ? arguments[1] : undefined, 3);
  	        var entry;
  	        while (entry = entry ? entry.n : this._f) {
  	          f(entry.v, entry.k, this);
  	          // revert to the last existing entry
  	          while (entry && entry.r) {
  	            entry = entry.p;
  	          }
  	        }
  	      }
docs: 23.2.3.6 Set.prototype.forEach(callbackfn, thisArg = undefined) 23.1.3.5 Map.prototype.forEach(callbackfn, thisArg = undefined)