\begin{Schunk}
\begin{Sinput}
 ees <- grep("ee", dat$z, value = TRUE, fixed = TRUE)
 head(ees)
\end{Sinput}
\begin{Soutput}
[1] "eenie" "eenie" "eenie" "eenie" "eenie" "eenie"
\end{Soutput}
\end{Schunk}
