One-shot compression and decompression is provided through the
compress() and decompress() functions.
Compress data in one shot. If you want to compress data sequentially,
use an instance of BZ2Compressor instead. The compresslevel
parameter, if given, must be a number between 1 and 9;
the default is 9.
Decompress data in one shot. If you want to decompress data
sequentially, use an instance of BZ2Decompressor instead.