an item for the blue value in RGB model or lightness in HSL model / brightness in HSB model
(to let blank if first item contains list of all values)
* @param {value[?]=0} minimum value if the light is off; single value or list of values for each component (optional, default 0)
* @param {value[?]=255} maximum value if the light is full on; single value or list of values for each component (optional, default 255 for rgb, [360,100,100] for hsl & hsv)
* @param {value=7} number of shades per color (optional, def