extensions/notebook-renderers/src/color.ts/Color/constructor
class Color:	constructor(arg: RGBA | HSLA | HSVA) {
		if (!arg) {
			throw new Error('Color needs a value');
		} else if (arg instanceof RGBA) {
			this.rgba = arg;
		} else if (arg instanceof HSLA) {
			this._hsla = arg;
			this.rgba = HSLA.toRGBA(arg);
		} else if (arg instanceof HSVA) {
			this._hsva = arg;
			this.rgba = HSVA.toRGBA(arg);
		} else {
			throw new Error('Invalid color ctor argument');
		}
	}