In N.L.R.B. v. Bakery Confectionery Wkrs., 3 Cir., 245 F.2d 211, relied upon by Union, the bylaws fixing dues were couched in terms of allowing a discount from the stated monthly dues figure, if payment was made before the last day of the month in which dues were payable. The Third Circuit viewed this structure as affording the member an option to receive a benefit and the member's failure to take advantage of the discount could in no way be deemed as an assessment of a penalty.