\frametitle {Basic looping}
  \begin{lstlisting}
# Fibonacci series:
# the sum of two elements
# defines the next
a, b = 0, 1
while b < 10:
    print b,
    a, b = b, a + b

\end{lstlisting}
\typ{1 1 2 3 5 8}\\
\alert{Recall it is easy to write infinite loops with \kwrd{while}}
  \inctime{20}