@classmethod
def DeregisterFormatter(cls, formatter_class):
    """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.
    """
    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]
    if formatter_data_type in cls._formatter_objects:
        del cls._formatter_objects[formatter_data_type]
