def yield_lines(iterable):
    """Converts an arbitrary bytes iterable into an iterable that yields whole
    lines. The final byte of each returned value (except possibly the last one)
    is a newline or carriage return character. The concatenation of the input
    iterable equals the concatenation of the output iterable."""
    buff = b""
    for data in iterable:
        buff += data
        parts = buff.splitlines(True)
        buff = parts.pop()
        yield from parts
    if buff:
        yield buff

def decompress_stream(iterable, decompressor):
    """Decompress an iterable of bytes using the given decompressor into
    another (decompressed) iterable of bytes. The decompressor can be a
    bz2.BZ2Decompressor or lzma.LZMADecompressor instance."""
    for data in iterable:
        data = decompressor.decompress(data)
        yield data
    if hasattr(decompressor, "flush"):
        yield decompressor.flush()