old_contents: msg = 'This is not yet implemented'
  
  def validate(sketch):
      """
      - sketch: a `dict`
      """
      raise NotImplementedError(msg)
  
  def readsketch_iter(iterable):
      """
      - iterable: as return by ijson.parser
  
      Returns a `dict` with a sketch information
      """
      raise NotImplementedError(msg)
  
  def readjamschema(schema):
      """
      Read a JAM definition schema
      """
      raise NotImplementedError(msg)
      
  
new_contents: MSG = 'This is not yet implemented'
  
  
  def validate(sketch):
      """
      - sketch: a `dict`
      """
      raise NotImplementedError(MSG)
  
  
  def readsketch_iter(iterable):
      """
      - iterable: as return by ijson.parser
  
      Returns a `dict` with a sketch information
      """
      raise NotImplementedError(MSG)
  
  
  def readjamschema(schema):
      """
      Read a JAM definition schema
      """
      raise NotImplementedError(MSG)
      
  
subject: Rename msg -> MSG (since a constant).