If you need your user's country of origin, there are many ways you can go about obtaining it programmatically. Some may opt for a simple drop-down that prompts the user to specify his/her country. If you don't want to burden your user this way, you might look at their session data and return their country of origin, time zone, or some other useful information. If you have fancy enough APIs at your disposal, you could even reverse geocode the user's longitude/latitude position and obtain an address.

I'm an old person. It's the sort of thing that happens when you aren't looking. All the kids these days are writing Slack and Discord bots in JavaScript, and I remember writing my first chatbots in Perl and hooking them into IRC. Fortunately, all the WTFs in my Perl chatbots have been lost to time.

"P" has a peer who wants to scrape all the image URLs out of a Discord chat channel. Those URLs will be fetched, then passed through an image processing pipeline to organize and catalog frequently used images, regardless of their origin.

Defensive programming is an important tool in any developer's toolbox. In strictly typed languages, types themselves provide a natural defense against certain classes of bugs, but in loosely typed languages, you may have to be more clear about your assumptions.

For example, in Python, you might choose to use the assert keyword to, well, assert that something is true. It's often used in debugging, but it's also a good way to ensure that the state of the parameters passed to a function, or some other state of your system is correct before doing anything else. If it's not, the code raises an exception.

Optional parameters are a great tool for building flexible APIs. In most languages, they're not strictly necessary- if you have function overloading, the difference between optional parameters and an overloaded function is just the quantity of boilerplate- but they're certainly a nice to have.

Well, they're a nice to have in the right hands.

Bad date handling code is like litter: offensive, annoying, but omnipresent. Nobody is specifically responsible for it, nobody wants to clean it up, and we end up ignoring it.

Murtaza K offers up a particularly malodorous example, though, that's worthy of note. It's got everything: string mangling, assumptions that ignore locale, bad ternaries, and it's completely unnecessary.