old_contents: """calc.py: A simple Python calculator."""
  import sys
  
  def add_all(nums):
  	return sum(nums)
  
  def multiply_all(nums):
  	return reduce(lambda a, b: a * b, nums)
  
  if __name__ == '__main__':
  	command = sys.argv[1]
  	nums = map(float, sys.argv[2:])
  	if command == 'add':
  		print(add_all(nums))
  	elif command == 'multiply':
  		print(multiply_all(nums))
  
new_contents: """calc.py: A simple Python calculator."""
  import sys
  
  def add_all(nums):
  	return sum(nums)
  
  def multiply_all(nums):
  	return reduce(lambda a, b: a * b, nums)
  
  if __name__ == '__main__':
  	command = sys.argv[1]
  	nums = map(float, sys.argv[2:])
  	if command == 'add':
  		print(add_all(nums))
  	elif command == 'multiply':
  		print(multiply_all(nums))
  	else:
  		usage = "calc.py [add|multiply] NUM1 [NUM2 [NUM3 [...]]]"
  		print(usage)
  
subject: Add usage string