I'm too stupid to see how this is either practical or relevant in a loosely typed language. The example was making assumptions that it is an array with integers

I'm too stupid to see how this is either practical or relevant in a loosely typed language. The example was making assumptions that it is an array with integers. It was also making an assumption a hacker is not hijacking your code to put strange values into your array etc. This reminds of John Resig's super complicated tricky JavaScript examples only a very small number of people would even care to try to understand but slightly less purposeful. Probably good for that type of crowd.