\begin{Verbatim}[commandchars=\\\{\}]
\PYG{c+c1}{\PYGZsh{} Short arrow heads:}
\PYG{n}{gd\PYGZus{}feature\PYGZus{}set}\PYG{o}{.}\PYG{n}{add\PYGZus{}feature}\PYG{p}{(}\PYG{n}{feature}\PYG{p}{,} \PYG{n}{sigil}\PYG{o}{=}\PYG{l+s+s2}{\PYGZdq{}ARROW\PYGZdq{}}\PYG{p}{,} \PYG{n}{color}\PYG{o}{=}\PYG{l+s+s2}{\PYGZdq{}blue\PYGZdq{}}\PYG{p}{,} \PYG{n}{arrowhead\PYGZus{}length}\PYG{o}{=}\PYG{l+m+mf}{0.25}\PYG{p}{)}
\PYG{c+c1}{\PYGZsh{} Or, longer arrow heads:}
\PYG{n}{gd\PYGZus{}feature\PYGZus{}set}\PYG{o}{.}\PYG{n}{add\PYGZus{}feature}\PYG{p}{(}\PYG{n}{feature}\PYG{p}{,} \PYG{n}{sigil}\PYG{o}{=}\PYG{l+s+s2}{\PYGZdq{}ARROW\PYGZdq{}}\PYG{p}{,} \PYG{n}{color}\PYG{o}{=}\PYG{l+s+s2}{\PYGZdq{}orange\PYGZdq{}}\PYG{p}{,} \PYG{n}{arrowhead\PYGZus{}length}\PYG{o}{=}\PYG{l+m+mi}{1}\PYG{p}{)}
\PYG{c+c1}{\PYGZsh{} Or, very very long arrow heads (i.e. all head, no shaft, so triangles):}
\PYG{n}{gd\PYGZus{}feature\PYGZus{}set}\PYG{o}{.}\PYG{n}{add\PYGZus{}feature}\PYG{p}{(}\PYG{n}{feature}\PYG{p}{,} \PYG{n}{sigil}\PYG{o}{=}\PYG{l+s+s2}{\PYGZdq{}ARROW\PYGZdq{}}\PYG{p}{,} \PYG{n}{color}\PYG{o}{=}\PYG{l+s+s2}{\PYGZdq{}red\PYGZdq{}}\PYG{p}{,} \PYG{n}{arrowhead\PYGZus{}length}\PYG{o}{=}\PYG{l+m+mi}{10000}\PYG{p}{)}
\end{Verbatim}
