def maximum_difference_sort_value(contributions):
    """
    Auxiliary function to sort the contributions for the compare_plot.
    Returns the value of the maximum difference between values in contributions[0].

    Parameters
    ----------
    contributions: list
        list containing 2 elements:
        a Numpy.ndarray of contributions of the indexes compared, and the features' names.

    Returns
    -------
    value_max_difference : float
        Value of the maximum difference contribution.
    """
    if len(contributions[0]) <= 1:
        max_difference = contributions[0][0]
    else:
        max_difference = max(
            [
                abs(contrib_i - contrib_j)
                for i, contrib_i in enumerate(contributions[0])
                for j, contrib_j in enumerate(contributions[0])
                if i <= j
            ]
        )
    return max_difference