[pygame] Can't use BLEND_*

[110110010 <Josef.Horn@xxxxxxxxx>]

Hello pygamers :)
In my game i needed some light effects and I decided for blending(BLEND_ADD, BLEND_SUB,..). After a long time in which I tried to get it working I decided to google the right solution. Google has found something, but it still didn't work. I've tried to make my own script. I've made this:

from pygame import *
init()
s=display.set_mode((800,600))
img=image.load("sunshine.png").convert_alpha()
while 1:
  event.pump()
  s.fill((0,0,0))
  s.blit(img,(0,0),None,1)# '1' means BLEND_ADD - That's what I've found somewhere
  display.flip()

But it raises me this:
  File "C:\Documents and Settings\Hornychovi\Plocha\Novy1.py", line 8, in <module>
    s.blit(img,(0,0),None,1)
TypeError: function takes at most 3 arguments (4 given)

can somebody help me? Any solutions? ... Please help :) Thank you :)