old_contents: class Error(Exception):
      pass
  
  class UnknownFileError(Error):
      pass
  
  class UnsupportedSettingError(Error):
      pass
  
  class NoSuchPageError(Error):
      pass
  
new_contents: class Error(Exception):
      pass
  
  class UnknownFileError(Error):
      pass
  
  class UnsupportedSettingError(Error):
      pass
  
  class NoSuchPageError(Error):
      pass
  
  class UnsupportedImageSizeError(Error):
      pass
  
subject: Add UnsupportedImageSizeError