@classmethod
def DeregisterDecompressor(cls, decompressor):
    """Deregisters a decompressor for a specific compression method.

    Args:
      decompressor (type): decompressor class.

    Raises:
      KeyError: if the corresponding decompressor is not set.
    """
    compression_method = decompressor.COMPRESSION_METHOD.lower()
    if compression_method not in cls._decompressors:
        raise KeyError('Decompressor for compression method: {0:s} not set.'
            .format(decompressor.COMPRESSION_METHOD))
    del cls._decompressors[compression_method]
