Check Image Monochromaticity

monochromatic or not monochromatic, that's the question.
This is the snippet if you need to check the monochromaticity of any image file.

Inspiration

We needed to make this validation at project I've worked on.

How does it look like?

Dependencies

PIL

Further work

I'm not sure if it works for all possible image formats.

If you use it and have any kind of problem, please let me know.