import lzma
import os


def sub3(f_in, f_out):
    with open(f_in, 'rb') as fd_in, open(f_out, 'wb') as fd_out:
        xz = lzma.LZMACompressor()
        file_size = os.path.getsize(f_in)
        file_size_dl = 0
        chunk_len = 1024 * 4
        for chunk in iter(lambda: fd_in.read(chunk_len), b''):
            file_size_dl += len(chunk)
            fd_out.write(xz.compress(chunk))
            print(u'Decompressing {size:4d}MB [{percent:.2f}%] {file_name}'.format(size=file_size_dl/1024,
                                                                                   percent=100.0*file_size_dl/file_size,
                                                                                   file_name=f_in)