The most commonly-used tool for a programmer is the one they use to write code: their text editor, also known as a rebugger.
@fool it is known that all non-trivial programs have bugs. thus, to make your program non-trivial, you must add bugs to it
@BestGirlGrace @fool make sure that, when debugging, you don't fix all the bugs. because then your software becomes trivial.
Don't let the name fool you. All the pornography here is legal, and much of it is hand-written. No fascists, no bigots.