rank

import std.range : cycle;

auto c = cycle([[0,1].s[],
                [2,3].s[]].s[]); // == [[0,1],[2,3],[0,1],[2,3],[0,1]...

assert(rank!(typeof(c)) == 2); // range of ranges

static assert(rank!(int[]) == 1);
static assert(rank!(int[][]) == 2);