PIL - drawing text and saving

I have created this program:

from PIL import Image, ImageDraw

a = Image.open(r'C:\Users\damian\Desktop\a.png')
draw = ImageDraw.Draw(a)
draw.text((1, 1), 'Hello World!')
a.save(r'C:\Users\damian\Desktop\a.png', "PNG")

In theory it should load image, draw text on it and save it b开发者_开发问答ut when I run it nothing happens. Can someone have a look and advise?

Edit.

I've solved this, it seems default colour is white and drawn text wasn't visible on my white image, fill="black" was needed.

This question can now be closed.

I've solved this, it seems default colour is white and drawn text wasn't visible on my white image, fill="black" was needed.

This question can now be closed.