KCL: Another example of how to use hex color strings (#7195)

rust/kcl-derive-docs/src/example_tests.rs

@@ -46,6 +46,7 @@ pub const TEST_NAMES: &[&str] = &[
     "std-appearance-hexString-0",
     "std-appearance-hexString-1",
     "std-appearance-hexString-2",
+    "std-appearance-hexString-3",
     "std-array-map-0",
     "std-array-map-1",
     "std-array-pop-0",

rust/kcl-lib/std/appearance.kcl

@@ -56,6 +56,37 @@
 /// grid(offset = 0, red = 0)
 /// ```
 ///
+/// ```kcl
+/// sideLen = 30
+/// n = 4
+/// 
+/// fn cube(offset, i, red) {
+///   x = floor(i / n)
+///   y = rem(i, divisor = n)
+///   g = 255 / n * x
+///   b = 255 / n * y
+///   return startSketchOn(offsetPlane(XY, offset))
+///     |> circle(diameter = sideLen, center = [sideLen * x * 1.5, sideLen * y * 1.5])
+///     |> extrude(length = sideLen)
+///     |> appearance(color = appearance::hexString([red, g, b]), metalness = 80, roughness = 40)
+/// }
+/// 
+/// fn grid(offset, red) {
+///   return map(
+///     [0 ..< n * n],
+///     f = fn(@i) {
+///       return cube(offset, i, red)
+///     },
+///   )
+/// }
+/// 
+/// map(
+///   [0..<n],
+///   f = fn(@i) {
+///     return grid(offset = i * sideLen * 2, red = 255 * i / n)
+///   },
+/// )
+/// ```
 @(impl = std_rust)
 export fn hexString(
   /// The red, blue and green components of the color.