def __init__(self, mode: str) -> None:
        """
        Args:
            mode (str): Optionals include "cls" and "mean". If set to "cls", it assumes
                the first element in the input is the cls token and returns it. If set
                to "mean", it returns the mean of the entire sequence.
        """
        super().__init__()
        assert mode in ["mean"], "Unsupported mode for SequencePool."
        self.mode = mode

        Args:
            mode (str): Optionals include "cls" and "mean". If set to "cls", it assumes
                the first element in the input is the cls token and returns it. If set
                to "mean", it returns the mean of the entire sequence.
        
python/aitemplate/frontend/nn/head.py