old_contents: def convert(number):
      ret = ""
      if number % 3 == 0:
          ret += "Pling"
      if number % 5 == 0:
          ret += "Plang"
      if number % 7 == 0:
          ret += "Plong"
      if ret == "":
          ret = str(number)
      return ret
  
new_contents: raindrops = {3: "Pling", 5: "Plang", 7: "Plong"}
  def convert(number):
      ret = ""
      
      for key, value in raindrops.items():
          if number % key == 0:
              ret += value
  
      if ret == "":
          ret = str(number)
      return ret
  
subject: Use dict