\begin{frame}
  \frametitle{Example Transaction}
  
  \begin{center}\vspace{-6ex}
    \includegraphics[width=3cm]{images/creditcards.jpg}
  \end{center}\vspace{-3ex}
  A withdrawal of $100$ euro causes the ATM to perform 
  a \emph{transaction in the bank's database}.
  \medskip
  
  \begin{exampleblock}{ATM Transaction}
    $\var{balance} \set \fun{read}(\var{account})$\\
    $\var{balance} \set \var{balance}-100$\\
    $\fun{write}(\var{account}, \var{balance})$\\
  \end{exampleblock}
  \pause\bigskip
  
  The account is properly updated to reflect the new balance.
\end{frame}