text: 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)
  