Add reference to "void pop();"

VL1.tex

@@ -187,7 +187,7 @@ It's all about \emph{input} and \emph{output} of functions! And that's it. Nothi
 \item everything (variables, data structures...) is \emph{immutable}
 \item expressions never have side-effects (remember: mathematical functions)
 \item same input $\mapsto$ same output... \emph{always}!
-\item replace a function with it's (return) value? Yes. (what happens in C or java if you do that?)
+\item replace a function with it's (return) value? Yes. What happens in C or java if you do that? Remember \code{void pop();}?
 \end{itemize}
 \onslide<+->
 \vspace{\baselineskip}