\begin{Schunk}
\begin{Sinput}
 bdraw()
 # code 3 is both ways
 arrows(x0 = -1, y0 = -1, x1 = 2, y1 = 4, length = 0.1, code = 3)
 # code 2 points forwards
 arrows(x0 = -4, y0 = -4, x1 = -2, y1 = 4, length = 0.3, code = 2)
 # code 1 is backwards
 arrows(x0 = 4.5, y0 = -8, x1 = -3, y1 = 18, length = 0.15, code = 1)
\end{Sinput}
\end{Schunk}
