def _make_sentence(self, tokens_left, tokens_right, seq_length=128):
    len_left = len(tokens_left)
    len_right = len(tokens_right)

    cut_len = len_left + len_right - (seq_length - 1)
    if cut_len > 0:
        cut_left = len_left - seq_length // 2
        cut_right = len_right - (seq_length - 1) // 2
        if cut_left < 0:
            cut_left, cut_right = 0, cut_left + cut_right
        elif cut_right < 0:
            cut_left, cut_right = cut_left + cut_right, 0
    else:
        cut_left, cut_right = 0, 0

    tokens_left = tokens_left[cut_left:]
    # tokens_right = tokens_right[:-cut_right]
    tokens_right = tokens_right[:len(tokens_right) - cut_right]

    tokens = tokens_left + [self.bert_tokenizer.mask_token] + tokens_right
    attention_mask = [1] * len(tokens_left) + [1] + [1] * len(tokens_right)

    if len(tokens) < seq_length:
        num_padding = seq_length - len(tokens)
        tokens += [self.bert_tokenizer.pad_token] * num_padding
        attention_mask += [0] * num_paddi