Method set_down

src/input.rs:203–209

(&mut self, button: T)

    }

    fn set_down(&mut self, button: T) {
        let was_up = self.down.insert(button);

        if was_up {
            self.pressed.insert(button);
        }
    }

    fn set_up(&mut self, button: T) {
        let was_down = self.down.remove(&button);