def METHOD_NAME(
    xdata: Union[np.ndarray, list], ydata: Union[np.ndarray, list], **kwargs
) -> tuple[tuple, tuple]:
    """Calculate 2 exponentials on top of each other, fit to the given ydata.
    No linear offset, the ESPRIT algorithm is used to identify the two exponential decays.
    Args:
        xdata (Union[np.ndarray, list]): The x-labels.
        ydata (Union[np.ndarray, list]): The data to be fitted
    Returns:
        tuple[tuple, tuple]: (A1, A2, f1, f2) with f* the decay parameters.
    """
    return fit_expn_func(xdata, ydata, 2)