\begin{Schunk}
\begin{Sinput}
 bdraw <- function() {
      plot(x = c(-5, 5), y = c(-10, 20), 
          type = "n", xlab = "", ylab = "")
  }
 bdraw()
 points(x = x, y = y)
\end{Sinput}
\end{Schunk}
