The `array_filter` function from the PHP standard library does not re-index the array; therefore, we must call `array_value`.
Why TDD?
Safety net for refactoring.
Safety net for re-engineering.
Executable documentation for our APIs and interactions.
Why NOT TDD?
Prove correctness or completeness.
These are unscripted, unrehearsed, mostly unedited, and with minimal prep-work. A more raw look at software development. This was started with a new user on my laptop; so, local settings and shortcuts are not present and will be introduced as we go. Basically, imagine pair or mob programming from a fresh laptop and a pretty big time delay.