How to use the apkutils.dex.byteio.Reader function in apkutils

def stream(self, offset):
        return Reader(self.raw, offset)

def __init__(self, data, flag=True):
        self.raw = data
        self.u16s = array.array('H', data[:len(data) & ~1])
        assert(self.u16s.itemsize == 2)
        self.u32s = array.array('I', data[:len(data) & ~3])
        assert(self.u32s.itemsize == 4)

        stream = Reader(data)

        # parse header
        # magic = stream.read(4)  # magic
        # magic_vers = stream.read(4)  # magic_vers
        # checksum = stream.u32()  # adler32 checksum
        # import binascii
        # sha1 = binascii.b2a_hex(stream.read(20)).decode('utf-8')
        stream.read(32)  # skip 32(magic, magic_vers, checksum, sha1)

        if stream.u32() != len(self.raw):
            print('Warning, unexpected file size!')

        if stream.u32() != 0x70:
            print('Warning, unexpected header size!')

        if stream.u32() != 0x12345678: