old_contents: # V1
  print(sum(i for i in range(1000) if not i % 3 or not i % 5))
  
  
  # V2
  print(sum(set(range(0,1000,3))|set(range(0,1000,5))))
  
new_contents: # V1
  print(sum(i for i in range(1000) if not i % 3 or not i % 5))
  
  # V2
  print(sum(set(range(0,1000,3))|set(range(0,1000,5))))
  
subject: Update 01.py