   end
 
   defp dec([c|cs], acc) when c >= "0" and c <= "9" do
-    <<c, b :: binary>> = c
+    <<c, _ :: binary>> = c
     d = c - ?0
     dec(cs, acc * 10 + d)
   end

  def parse(s) do
    [v] = parse(String.codepoints(iolist_to_binary(s)), [])
    v
  end
  defp parse([], v) do
    v

  # defp parse([?x|cs], stk) do
    # hex(cs, stk)
  # end
  defp parse(["-"|cs], [d|stk]) do
    parse(cs, [-d|stk])
  end
  defp parse(["e"|cs], [x,d|stk]) do
    parse(cs, [d / :math.pow(10, x)|stk])
  end
  defp parse(["{"|cs] , stk) do
