Never trust a users input!

Never underestimate how dumb your dumbest user could be.

Kinda fits in nicely ^^

Did little Bobby Tables pay you a visit?

Further more, never trust outside input of any sort.

Even if it’s two api endpoints that just call one another with no user interaction - guarantee that one time it goes horribly wrong it could have been prevented with a bit of validation...

Or get ready for for a fucking #NullPointerException

The paradox of machine learning.

One of the best pieces of advice ever. I think it's a mark of a great developer to account for anything the user could possible enter.

Never trust a user!