old_contents: #!/usr/bin/env python
  """A Python calculator"""
  import sys
  
  command = sys.argv[1]
  numbers = [float(a) for a in sys.argv[2:]]
  a = float(sys.argv[2])
  b = float(sys.argv[3])
  
  
  if command == 'add':
      print sum(numbers)
  
  elif command == 'multiply':
      product = 1
      for num in numbers:
          product *= num
      print product
  elif command == 'divide':
      div = 1
      if b != 0: 
          div = a/b
          print div 
  
  
new_contents: #!/usr/bin/env python
  """A Python calculator"""
  import sys
  
  command = sys.argv[1]
  numbers = [float(a) for a in sys.argv[2:]]
  a = float(sys.argv[2])
  b = float(sys.argv[3])
  
  
  if command == 'add':
      print sum(numbers)
  
  elif command == 'multiply':
      product = 1
      for num in numbers:
          product *= num
      print product
  elif command == 'divide':
      div = 1
      if b != 0: 
          div = a/b
          print div 
  
  print ':)'
  
subject: Add smiley face to output