@classmethod
def GetDecompressor(cls, compression_method):
    """Retrieves the decompressor object for a specific compression method.

    Args:
      compression_method (str): compression method identifier.

    Returns:
      Decompressor: decompressor or None if the compression method does
          not exists.
    """
    compression_method = compression_method.lower()
    decompressor = cls._decompressors.get(compression_method, None)
    if not decompressor:
        return None
    return decompressor()
