--- a/slides/slides09.tex	Tue Dec 14 11:40:31 2021 +0000
+++ b/slides/slides09.tex	Wed Dec 15 19:00:01 2021 +0000
@@ -58,7 +58,7 @@
 
 \footnotesize
 \begin{textblock}{13}(0.9,3)
-\begin{lstlisting}[]numbers=none]
+\begin{lstlisting}[numbers=none]
 def fib(n) = if n == 0 then 0 
              else if n == 1 then 1 
              else fib(n - 1) + fib(n - 2);