To practice filling part of an image with a nested for loop, write a program that creates a $32$ by $24$ black and white image of the following pattern:

Pixel grid in quarters: top left and bottom right are black.

This pattern is evenly divided into four sections $($therefore each section is $12$ pixels tall and $16$ pixels wide$).$

Your program should create this image and save it as 'output.png$\text{'}.$