code: def initialize():
      
      for pin in sorted(OUTPUT_PINS.values()):
          _enable_pin(pin, OUT)
  
      for pin in sorted(INPUT_PINS.values()):
          _enable_pin(pin, IN)
docs: All named pins in OUTPUT_PINS and INPUT_PINS are exported, and set the
      HALT pin high (normal running state), since the default value after export
      is low.