julia> function hanoi(n, source, dest, spare)
          if n == 1
              println("Move disk 1 from rod $source to rod $dest")
          else n >= 2
              hanoi(n - 1, source, spare, dest)
              println("Move disk $n from rod $source to rod $dest")
              hanoi(n - 1, spare, dest, source)
          end
       end
hanoi (generic function with 1 method)

julia> hanoi(3, "A", "B", "C")
Move disk 1 from rod A to rod B # step 1, recurse
Move disk 2 from rod A to rod C # step 2, recurse
Move disk 1 from rod B to rod C # step 3, recurse
Move disk 3 from rod A to rod B # base case, n == 1
Move disk 1 from rod C to rod A # step 1, recurse
Move disk 2 from rod C to rod B # step 2, recurse
Move disk 1 from rod A to rod B # step 3, recurse

julia> hanoi(4, "A", "B", "C")
Move disk 1 from rod A to rod C # step 1
Move disk 2 from rod A to rod B # step 2
Move disk 1 from rod C to rod B # step 3
Move disk 3 from rod A to rod C # base case
Move disk 1 from rod B to rod A # 1
Move disk 2 from rod B to rod C # 2
Move disk 1 from rod A to rod C # 3
Move disk 4 from rod A to rod B # base case
Move disk 1 from rod C to rod B # 1
Move disk 2 from rod C to rod A # 2
Move disk 1 from rod B to rod A # 3
Move disk 3 from rod C to rod B # base case
Move disk 1 from rod A to rod C # 1
Move disk 2 from rod A to rod B # 2
Move disk 1 from rod C to rod B # 3