Python help input a parameter in the function for image manipulation

def rotate():

for x in range(w):

for y in range(h):

px = img.getpixel((x, y))

target_x = (h - 1) - y

img.putpixel((target_x, x), px)

rotate()

img.save("rotate.jpeg")

I need to use the parameter "img" and "degrees" degrees will be 90, 180 or 270