       end) == "0 1 2 3 4 5 6 7 8 9 "
     end
 
+    test "print stack (peek)" do
+      assert capture_io(fn ->
+        RPNForthThing.initialize(~w[ 1 2 3 rot .s ])
+      end) == "2 3 1 "
+    end
+
     test "print stars" do
       # example from https://github.com/dsevilla/uForth
       assert capture_io(fn ->

      assert RPNForthThing.initialize(~w[1 2 +]) === 3
    end

    test "subtracting 2 numbers" do
      assert RPNForthThing.initialize(~w[3 2 -]) === 1
    end

    test "multiplying 2 numbers" do
      assert RPNForthThing.initialize(~w[3 2 *]) === 6
    end

    test "dividing 2 numbers" do
      assert RPNForthThing.initialize(~w[3 2 /]) === 1
    end

    test "sequence of simple math operations" do
      assert RPNForthThing.initialize(~w[ 1 2 3 4 5 * + + + 2 /]) === 13
    end

      # assert RPNForthThing.initialize(~w[ 3 5 < ? 33 44 ]) == 33
      assert RPNForthThing.initialize(~w[ 3 5 > if 33 else 44 then ]) == 44
      # assert RPNForthThing.initialize(~w[ 3 5 > ? 33 44 ]) == 44
    end

    test "nested if else then" do
      assert capture_io(fn ->
        RPNForthThing.initialize(~w[ 5 dup 3 < if ." greater " else 7 < if ." lesser " else ." equal " then then ])
      end) == "lesser"
    end

    test "if then, NO else" do
