   end
 
   # In-place decrement
-  def compute([ "--" | remaining_input], [x | stack], dict) do
+  def compute([ "1-" | remaining_input], [x | stack], dict) do
     compute(remaining_input, [(x - 1) | stack], dict)
   end
 
   # In-place increment
-  def compute([ "++" | remaining_input], [x | stack], dict) do
+  def compute([ "1+" | remaining_input], [x | stack], dict) do
     compute(remaining_input, [(x + 1) | stack], dict)
   end
 

  end

  # Comments
  def compute([ "#" | remaining_input ], stack, dict) do
    {_, [";" | remainder]} = Enum.split_while(remaining_input, fn(ins) -> ins != ";" end)
    compute(remainder, stack, dict)
  end


    end

    test "increment and decrement" do
      assert RPNForthThing.initialize(~w[ 3 1+ ]) == 4
      assert RPNForthThing.initialize(~w[ 3 1- ]) == 2
    end

    test "unary negation" do
      assert RPNForthThing.initialize(~w[ -3 @- ]) == 3
    end

    test "if else then" do
      assert RPNForthThing.initialize(~w[ 3 5 < if 33 else 44 then ]) == 33
      # 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 "and or not" do
