def _toolkit_get_topk_bottomk(values, k=5):
    """
    Returns a tuple of the top k values from the positive and
    negative values in a SArray

    Parameters
    ----------
    values : SFrame of model coefficients

    k: Maximum number of largest positive and k lowest negative numbers to return

    Returns
    -------
    (topk_positive, bottomk_positive) : tuple
            topk_positive : list
                floats that represent the top 'k' ( or less ) positive
                values
            bottomk_positive : list
                floats that represent the top 'k' ( or less ) negative
                values
    """
    top_values = values.topk('value', k=k)
    top_values = top_values[top_values['value'] > 0]
    bottom_values = values.topk('value', k=k, reverse=True)
    bottom_values = bottom_values[bottom_values['value'] < 0]
    return top_values, bottom_values
