message: Derivative of rgb wrt value.
diff: @@ -188,5 +188,12 @@ def _rgb_to_hsv_grad(op, grad):
  green_smallest = cast((greens <= reds) & (greens < blues), dtypes.float32)
  blue_smallest = cast((blues <= reds) & (blues <= greens), dtypes.float32)
  + ##############################################################
  + # Derivatives of R, G, B wrt Value slice
  + ##############################################################
  + dv_dr = red_biggest
  + dv_dg = green_biggest
  + dv_db = blue_biggest
  +
  return None
  