\begin{Verbatim}[commandchars=\\\{\}]
\PYG{g+gp}{\PYGZgt{}\PYGZgt{}\PYGZgt{} }\PYG{n}{counts}\PYG{p}{[}\PYG{l+s+s1}{\PYGZsq{}U\PYGZsq{}}\PYG{p}{]}
\PYG{g+gt}{Traceback (most recent call last):}
    \PYG{o}{...}
\PYG{g+gr}{IndexError}: \PYG{n}{\PYGZsq{}U\PYGZsq{}}
\PYG{g+gp}{\PYGZgt{}\PYGZgt{}\PYGZgt{} }\PYG{n}{counts}\PYG{p}{[}\PYG{l+s+s1}{\PYGZsq{}X\PYGZsq{}}\PYG{p}{]} \PYG{o}{=} \PYG{l+m+mi}{6}
\PYG{g+gt}{Traceback (most recent call last):}
    \PYG{o}{...}
\PYG{g+gr}{IndexError}: \PYG{n}{\PYGZsq{}X\PYGZsq{}}
\PYG{g+gp}{\PYGZgt{}\PYGZgt{}\PYGZgt{} }\PYG{n}{counts}\PYG{p}{[}\PYG{l+m+mi}{7}\PYG{p}{]}
\PYG{g+gt}{Traceback (most recent call last):}
    \PYG{o}{...}
\PYG{g+gr}{IndexError}: \PYG{n}{index 7 is out of bounds for axis 0 with size 4}
\end{Verbatim}
