code: function shadeColor(col, amount) {
    let col1rgb = parseColor(col);
    return RGBobj2string({
      r: Math.min(255, col1rgb.r * amount + 0 * Math.max(0,1-amount)),
      g: Math.min(255, col1rgb.g * amount + 0 * Math.max(0,1-amount)),
      b: Math.min(255, col1rgb.b * amount + 0 * Math.max(0,1-amount)),
      a: col1rgb.a
    });
  }
docs: Shade the colour by the given amount.