import pyb
from pyb import LED

for i in range(4):
    print(LED(i+1))

for i in range(4):
    LED(i+1).on()
pyb.delay(10)
for i in range(4):
    LED(i+1).off()
pyb.delay(10)
for i in range(4):
    LED(i+1).toggle()
pyb.delay(10)
for i in range(4):
    LED(i+1).intensity(0)

for i in range(256):
    LED(4).intensity(i)
    if LED(4).intensity() != i:
        print('fail', i)
    pyb.delay(1)
for i in range(256):
    LED(4).intensity(255 - i)
    pyb.delay(1)

for i in range(4):
    LED(i+1).off()

import pyb
from pyb import LED

l1 = pyb.LED(1)
l2 = pyb.LED(2)
l3 = pyb.LED(3)
l4 = pyb.LED(4)

leds = [LED(i) for i in range(1, 5)]
pwm_leds = leds[2:]

# test printing
for l in leds:
    print(l)

# test on and off
for l in leds:
    l.on()
    assert l.intensity() == 255
    pyb.delay(100)
    l.off()
    assert l.intensity() == 0
    pyb.delay(100)

# test toggle
for l in 2 * leds:
    l.toggle()
    assert l.intensity() in (0, 255)
    pyb.delay(100)

# test intensity
for l in pwm_leds:
    for i in range(256):
        l.intensity(i)
        assert l.intensity() == i
        pyb.delay(1)
    for i in range(255, -1, -1):
        l.intensity(i)
        assert l.intensity() == i
        pyb.delay(1)

Update pyboard LED test.