\begin{Verbatim}[commandchars=\\\{\}]
\PYG{g+gp}{\PYGZgt{}\PYGZgt{}\PYGZgt{} }\PYG{k+kn}{from} \PYG{n+nn}{Bio.Seq} \PYG{k+kn}{import} \PYG{n}{UnknownSeq}
\PYG{g+gp}{\PYGZgt{}\PYGZgt{}\PYGZgt{} }\PYG{n}{unk\PYGZus{}dna} \PYG{o}{=} \PYG{n}{UnknownSeq}\PYG{p}{(}\PYG{l+m+mi}{20}\PYG{p}{,} \PYG{n}{character}\PYG{o}{=}\PYG{l+s+s2}{\PYGZdq{}N\PYGZdq{}}\PYG{p}{)}
\PYG{g+gp}{\PYGZgt{}\PYGZgt{}\PYGZgt{} }\PYG{n}{unk\PYGZus{}dna}
\PYG{g+go}{UnknownSeq(20, character=\PYGZsq{}N\PYGZsq{})}
\PYG{g+gp}{\PYGZgt{}\PYGZgt{}\PYGZgt{} }\PYG{n+nb}{print}\PYG{p}{(}\PYG{n}{unk\PYGZus{}dna}\PYG{p}{)}
\PYG{g+go}{NNNNNNNNNNNNNNNNNNNN}
\end{Verbatim}
