def optimal_dtype(cardinality: Optional[int]) -> Type[numpy.number]:
        """Get the dtype to use for an index of a certain cardinality

        Args:
            cardinality (Optional[int]): The number of elements to be indexed

        Returns:
            Type[numpy.number]: The dtype to use for the index
        """
        if cardinality is not None and cardinality < 65500:
            return numpy.uint16
        else:
            return numpy.int32
Get the dtype to use for an index of a certain cardinality

        Args:
            cardinality (Optional[int]): The number of elements to be indexed

        Returns:
            Type[numpy.number]: The dtype to use for the index
        
finetune/core/datasets/indexed_dataset.py