> In the right-to-left flavor, do the integers start at 0 or end with 0? > I view this confusion as another argument for not passing the integer, but I > can live with it. (For the above, I guess that I would prefer that the int > arg be 0 on the last call of the unfolder, but again could handle either way.) They go from n - 1 to 0, i.e. they correspond to the index of the element.