There’s a missing dash between color and trio. However, we should probably refer to the exercise name, not the slug. The student would be more familiar with the name.
Elsewhere in that document, we refer to the inputs in the style of <color>-<color>-<color> or “<color>”, “<color>”, “<color>”. This could be consistently applied one way or the other.
Otherwise, it’s a great exercise I’m going to borrow for my tracks.