button on gamepad pad is held — a bit in the pad's button mask, in the SDL standard order (A/B/X/Y, bumpers, start, …).
```ludic
program Demo {
entry {
Input.set_pad(0, true, 1, 0.0, 0.0, 0.0, 0.0)
if Input.pad_button(0, 0) { print(1) }
}
}
```