earray8(io.BytesIO(b"\x03\x00\x00\x00\x00\x00\x00\x00abcdef"))
    bytearray(b'abc')
    >>> bigsize8 = struct.pack("<Q", sys.maxsize//3)
    >>> read_bytearray8(io.BytesIO(bigsize8 + b"abcdef"))  #doctest: +ELLIPSIS
    Traceback (most recent call last):
    ...
    ValueError: expected ... bytes in a bytearray8, but only 6 remain
    r