old_contents: #!/usr/bin/env python
  
  import serial, time, sys
  import datetime
  
  s = serial.Serial()
  s.baudrate = 9600
  s.timeout = 0
  s.port = "/dev/serial0"
  
  try:
      s.open()
  except serial.SerialException, e:
      sys.stderr.write("Could not open port %r: %s\n" % (s.port, e))
      sys.exit(1)
  
  s.write("$$$ALLL,OFFF\r")
  time.sleep(0.5)
  
  while True:
      currenttime = datetime.datetime.strftime(datetime.datetime.now(), '%H:$M:$S')
      
      s.write(currenttime+"\r")
      time.sleep(1)
  
new_contents: #!/usr/bin/env python
  
  import serial, time, sys
  import datetime
  
  s = serial.Serial()
  s.baudrate = 9600
  s.timeout = 0
  s.port = "/dev/serial0"
  
  try:
      s.open()
  except serial.SerialException, e:
      sys.stderr.write("Could not open port %r: %s\n" % (s.port, e))
      sys.exit(1)
  
  s.write("$$$ALLL,OFFF\r")
  time.sleep(0.5)
  
  while True:
      currenttime = datetime.datetime.strftime(datetime.datetime.now(), '%H:%M:%S')
      
      s.write(currenttime+"\r")
      time.sleep(1)
  
subject: Fix typos