Take a ladder with 5 steps, write a function that gives all the possible combinations of either 1,2, or 3 steps, in any order, to get to the 5th step, and returns the total number of combinations. So some of the possibilities would be [1,1,1,1,1], [1,1,1,2], [1,1,2,1], etc. Then he asked the same question with order not being considered, so [1,1,1,2] and [1,1,2,1] are the same solution.