\begin{knitrout}
\definecolor{shadecolor}{rgb}{0.969, 0.969, 0.969}\color{fgcolor}\begin{kframe}
\begin{alltt}
 \hlkwd{set.seed}\hlstd{(}\hlnum{123}\hlstd{)}
 \hlstd{x} \hlkwb{=} \hlkwd{runif}\hlstd{(}\hlnum{10}\hlstd{)}
 \hlkwd{sd}\hlstd{(x)}  \hlcom{# standard deviation}
\end{alltt}
\begin{verbatim}
## [1] 0.29474
\end{verbatim}
\begin{alltt}
 \hlkwd{Sys.sleep}\hlstd{(}\hlnum{3}\hlstd{)} \hlcom{# test cache}
\end{alltt}
\end{kframe}
\end{knitrout}