Python random method

How can i here rgb_im = com4.convert('RGB') random method replace com4 with another? for example com3, or com2 or com1.
I tried several variations but none worked.

com1 = Image.alpha_composite(im1, im2)

com2 = Image.alpha_composite(com1, im3)

com3 = Image.alpha_composite(com2, im4)

com4 = Image.alpha_composite(com3, im5)

#Convert to RGB

rgb_im = com4.convert('RGB')

file_name = str(item["tokenId"]) + ".png"

rgb_im.save("./images/" + file_name)