     initialize(System.argv)
   end
   def initialize(input) when is_binary(input) do
-    initialize(String.split(input, " ", trim: true))
+    initialize(String.split(input, ~r/\s+/))
   end
   def initialize(input) when is_list(input) do
     input |> normalize |> compute([], [], Map.new)

      # 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 "if then, NO else" do

        ])
      end) == "73 "
    end

    test "/mod" do
      assert capture_io(fn -> RPNForthThing.initialize(~w[
        22 4 /mod . .
      ]) end) == "5 2 "
    end

    # may be wrong
    test "*/mod" do
      assert RPNForthThing.initialize(~w[
        8 10 3 */mod
      ]) == [6, 3]
    end

    test "rand doesn't error" do
      rand = RPNForthThing.initialize(~w[ rand ])
      assert rand > 0
