def exkurt_fullsky(l):
    """
    Returns the excess kurtosis of the full-sky marginal likelihood for a given l.

    Args:
        l (int): The l to return the excess kurtosis for.
    Returns:
        float: Excess kurtosis of the full-sky marginal likelihood for this l.
    """
    nu = 2 * l + 1
    k = nu / 2.
    return 6 / k