How to save an image list in PDF using PIL (pillow)?

Try this format

from PIL import Image
im1 = PIL.Image.open("1.jpg").convert("RGB")
im2 = PIL.Image.open("2.jpg").convert("RGB")
im3 = PIL.Image.open("3.jpg").convert("RGB")
images = [im2,im3]
im1.save("out.pdf", save_all=True, append_images=images)

This problem is solved in PIL ver 5.0.0 (https://pillow.readthedocs.io/en/latest/).