def _estimate_step_number(n_points: int, batch_size: int) -> int:
    """Estimates which step this is (or rather how many steps were collected previously, basing on the ratio
    of number of points collected and the batch size).

    Note that this method is provisional and may be replaced with a parameter in the config.

    Raises:
        ValueError if ``n_points`` or ``batch_size`` is less than 1
    """
    if min(n_points, batch_size) < 1:
        raise ValueError(
            f"Both n_points={n_points} and batch_size={batch_size} must be at least 1."
        )  # pragma: no cover

    return n_points // batch_size