This example shows how to set the options for automatic syntax highlighting for code in LaTeX with the listings package (which provides the lstlisting environment). The listings package supports many languages, including Java, C, C++, MATLAB/Octave and Python, and you can set the language option globally with \lstset or for each listing, when you have listings in multiple languages.
A variant and a combination of Hering's and Zöllner's illusion. The red grid is completely straight all the time.
Submitted as an answer to the Showcase of Optical Illusions question on TeX SX.
Click the Illusions tag below to see more!