nl_tokens: ------------------------------------------------------------------- Harmony WeakSet
pl_tokens: function WeakSetConstructor ( iterable ) { if ( IS_UNDEFINED ( <mask> . target ) ) { throw MakeTypeError ( kConstructorNotFunction , "WeakSet" ) ; } % WeakCollectionInitialize ( this ) ; if ( ! IS_NULL_OR_UNDEFINED ( iterable ) ) { var adder = this . add ; if ( ! IS_CALLABLE ( adder ) ) { throw MakeTypeError ( kPropertyNotFunction , adder , 'add' , this ) ; } for ( var value of iterable ) { % _Call ( adder , this , value ) ; } } }