old_contents: def fence_pattern(rails, message_size):
      pass
  
  
  def encode(rails, message):
      pass
  
  
  def decode(rails, encoded_message):
      pass
  
new_contents: def encode(message, rails):
      pass
  
  
  def decode(encoded_message, rails):
      pass
  
subject: improve stub file (#1263)