Ensure that the axis argument passed to min, max, argmin, or argmax is
    zero or None, as otherwise it will be incorrectly ignored.

    Parameters
    ----------
    axis : int or None

    Raises
    ------
    ValueError

def validate_minmax_axis(axis):
    """
    Ensure that the axis argument passed to min, max, argmin, or argmax is
    zero or None, as otherwise it will be incorrectly ignored.

    Parameters
    ----------
    axis : int or None

    Raises
    ------
    ValueError
    """
    ndim = 1  # hard-coded for Index
    if axis is None:
        return
    if axis >= ndim or (axis < 0 and ndim + axis < 0):
        raise ValueError("`axis` must be fewer than the number of "
                         "dimensions ({ndim})".format(ndim=ndim))