old_contents: import warnings
  
  warnings.simplefilter('once', DeprecationWarning)
  
  
  class deprecated():
      """A decorator for warning about deprecation warnings.
  
      The decorator takes an optional message argument. This message can
      be used to direct the user to a new API or specify when it will
      be removed.
      """
  
      def __init__(self, message=None):
          self.message = message
  
      def __call__(self, f):
          def wrapped(*args, **kwargs):
              if self.message is None:
                  self.message = '{} is deprecated and will be removed soon.'.format(
                      f.__name__)
              warnings.warn(self.message, DeprecationWarning)
              return f(*args, **kwargs)
          return wrapped
  
new_contents: import warnings
  
  warnings.simplefilter('once', DeprecationWarning)
  
  
  class deprecated():
      """A decorator for warning about deprecation warnings.
  
      The decorator takes an optional message argument. This message can
      be used to direct the user to a new API or specify when it will
      be removed.
      """
  
      DEFAULT_MESSAGE = '{} is deprecated and will be removed soon.'
  
      def __init__(self, message=None):
          self.message = message
  
      def __call__(self, f):
          def wrapped(*args, **kwargs):
              if self.message is None:
                  self.message = self.DEFAULT_MESSAGE.format(
                      f.__name__)
              warnings.warn(self.message, DeprecationWarning)
              return f(*args, **kwargs)
          return wrapped
  
subject: Fix pep8