old_contents: 
  
  class MalformedFileError(Exception):
      """Error raised when the file is not well formatted"""
  
new_contents: 
  
  class MalformedFileError(Exception):
      """Error raised when the file is not well formatted"""
  
  
  class MalformedCaptionError(Exception):
      """Error raised when a caption is not well formatted"""
  
subject: Add new exception for malformed captions