This LaTeX code will trim off the right and left sides equally to make the document have the correct aspect ratio for A4 paper, and then the whole document is upscaled to have the correct physical dimensions too.
This is particularly useful in situations where an A4 document is printed on letter paper (usually resulting in smaller text and white bars padding the sides of the page) and later needs to be scanned into a PDF and merged with another document of A4 sized sheets.
Are there better ways to accomplish this same goal out there? Probably, but when I was in a pinch and needed this quick, a simple LaTeX file was my best solution.