def METHOD_NAME(l):
    head = 0xd7
    while head == 0xd7:
        head = random.randint(0xb0, 0xf7)
    body = random.randint(0xa1, 0xfe)
    val = f'{head:x} {body:x}'
    s = bytes.fromhex(val).decode('gb2312')
    VOCAB_SET.add(s)
    if l == 0:
        return s
    else:
        return s + METHOD_NAME(l-1)