code: def DeregisterFormatter(cls, formatter_class):
      
      formatter_data_type = formatter_class.DATA_TYPE.lower()
      if formatter_data_type not in cls._formatter_classes:
        raise KeyError(
            'Formatter class not set for data type: {0:s}.'.format(
                formatter_class.DATA_TYPE))
  
      del cls._formatter_classes[formatter_data_type]
docs: Deregisters a formatter class.
  
      The formatter classes are identified based on their lower case data type.
  
      Args:
        formatter_class (type): class of the formatter.
  
      Raises:
        KeyError: if formatter class is not set for the corresponding data type.