\begin{Verbatim}[commandchars=\\\{\}]
\PYG{g+gp}{\PYGZgt{}\PYGZgt{}\PYGZgt{} }\PYG{k}{assert} \PYG{n}{os}\PYG{o}{.}\PYG{n}{path}\PYG{o}{.}\PYG{n}{isfile}\PYG{p}{(}\PYG{n}{clustalw\PYGZus{}exe}\PYG{p}{),} \PYG{l+s+s2}{\PYGZdq{}Clustal W executable missing\PYGZdq{}}
\PYG{g+gp}{\PYGZgt{}\PYGZgt{}\PYGZgt{} }\PYG{n}{stdout}\PYG{p}{,} \PYG{n}{stderr} \PYG{o}{=} \PYG{n}{clustalw\PYGZus{}cline}\PYG{p}{()}
\end{Verbatim}
