'Args:
alpha(float): maximum saturation change.
rgb (bool): whether input is RGB or BGR.'

def __init__(self, alpha=0.4, rgb=None):

    super(Saturation, self).__init__()
    if (rgb is None):
        logger.warn('Saturation()    now    assumes    rgb=False,    but    will    by    default    use    rgb=True    in    the    future!')
        rgb = False
    rgb = bool(rgb)
    assert (alpha < 1)
    self._init(locals())
