def add_left_title(ax, title, **kwargs):
    """Add a centered title on the left of the selected axis.

    All :func:`~matplotlib.Axes.annotate` parameters are
    accessible.

    :param ax: Target plot axis.
    :type ax: :class:`~matplotlib.Axes`
    :param str title: Title text to add.

    :return: :class:`~matplotlib.text.Annotation`
    """
    if title is None:
        return
    kwargs.setdefault('xy', (0, 0.5))
    kwargs.setdefault('xytext', (-ax.yaxis.labelpad - 5, 0))
    kwargs.setdefault('xycoords', ax.yaxis.label)
    kwargs.setdefault('textcoords', 'offset points')
    kwargs.setdefault('ha', 'right')
    kwargs.setdefault('va', 'center')
    return ax.annotate(title, **kwargs)
