Metroid Samus Returns text

parse_btxt.py

def getstr(f):
    ret = "";char = f.read(1)
    while char != "\x00":
        ret += char
        char = f.read(1)
    return ret

def getustr(f):
    ret = "";char = f.read(2)
    while char != "\x00\x00":
        ret += char
        char = f.read(2)
    return ret

data = []
with open("japanese.txt", "rb") as f:
    # change this ^^^ to use
    assert f.read(4) == b"BTXT"
    assert f.read(4) == b"\x01\x00\x08\x00" #???
    f.seek(0, 2)
    size = f.tell()
    f.seek(8)
    while f.tell() < size:
        name = getstr(f)
        data.append(name.encode("UTF-16-LE"))
        name = getustr(f)
        data.append(name)
    with open("japanese1.txt", "wb") as o:
        # change this ^^^ to use
        o.write("\xFF\xFE")
        for line in data:
            o.write(line + "\r\n".encode("UTF-16-LE"))

Im try to translation this game and want to encrypt is back to binary. How can i do it with this?
And thanks for your hard work.