old_contents: #!/usr/bin/env python
  
  from blinkenlights import dimmer, setup, cleanup
  
  pin = 18
  
  setup(pin)
  
  up = range(10)
  down = range(9)
  down.reverse()
  
  bpm = 70
  
  period = 60.0 / bpm # seconds
  
  time_per_level = period / len(up + down)
  
  for i in range(10):
      for j in (up + down):
          brightness = (j+1) / 10.0
          dimmer(brightness, time_per_level, pin)
  
  cleanup()
  
new_contents: #!/usr/bin/env python
  
  from blinkenlights import dimmer, setup, cleanup
  
  pin = 18
  bpm = 70
  
  setup(pin)
  
  up = range(10)
  down = range(9)
  down.reverse()
  spectrum = up + down + [-1]
  
  period = 60.0 / bpm # seconds
  time_per_level = period / len(spectrum)
  
  for i in range(10):
      for j in (spectrum):
          brightness = (j+1) / 10.0
          dimmer(brightness, time_per_level, pin)
  
  cleanup()
  
subject: Add a 0.0 duty cycle: brief moment of off time.