from typing import List


def xlnet_tokens_pre_processor(token_ids: List[int]) -> List[int]:
    """Add XLNET style special tokens.

    Args:
        token_ids: List of token ids without any special tokens.

    Returns:
        List of token ids augmented with special tokens.
    """
    XLNET_CLS_ID = 3
    XLNET_SEP_ID = 4

    token_ids.append(XLNET_SEP_ID)
    token_ids.append(XLNET_CLS_ID)

    return token_ids