Another example: two buttons controlling an LED like an AND gate.

| Button A | Button B | LED |
|:--------:|:--------:|:---:|
| Released | Released | Off |
| Pressed  | Released | Off |
| Released | Pressed  | Off |
| Pressed  | Pressed  | On  |

## Procedural approach

```python
from gpiozero import LED, Button

led = LED(2)
button_a = Button(3)
button_b = Button(4)

while True:
    if button_a.is_pressed and button_b.is_pressed:
        led.on()
    else:
        led.off()
```

## Event-driven approach

```python
from gpiozero import LED, Button
from signal import pause

led = LED(2)
button_a = Button(3)
button_b = Button(4)

def both_pressed():
    if button_a.is_pressed and button_b.is_pressed:
        led.on()

button_a.when_pressed = both_presssed
button_a.when_released = led.off
button_b.when_pressed = both_pressed
button_b.when_released = led.off

pause()
```

## Declarative approach

```python
from gpiozero import LED, Button
from gpiozero.tools import all_avalues
from signal import pause

led = LED(2)
button_a = Button(3)
button_b = Button(4)

led.source = all_values(button_a.values, button_b.values)

pause()
```